diff --git a/src/cmap/handshake/client_metadata.ts b/src/cmap/handshake/client_metadata.ts
index 23dcaa4b0c3..295e1af078a 100644
--- a/src/cmap/handshake/client_metadata.ts
+++ b/src/cmap/handshake/client_metadata.ts
@@ -2,13 +2,30 @@ import * as os from 'os';
 import * as process from 'process';
 
 import { BSON, type Document, Int32 } from '../../bson';
-import { MongoInvalidArgumentError, MongoRuntimeError } from '../../error';
-import type { MongoOptions } from '../../mongo_client';
+import { MongoInvalidArgumentError } from '../../error';
+import type { DriverInfo, MongoOptions } from '../../mongo_client';
 import { fileIsAccessible } from '../../utils';
 
 // eslint-disable-next-line @typescript-eslint/no-require-imports
 const NODE_DRIVER_VERSION = require('../../../package.json').version;
 
+/** @internal */
+export function isDriverInfoEqual(info1: DriverInfo, info2: DriverInfo): boolean {
+  /** for equality comparison, we consider "" as unset */
+  const nonEmptyCmp = (s1: string | undefined, s2: string | undefined): boolean => {
+    s1 ||= undefined;
+    s2 ||= undefined;
+
+    return s1 === s2;
+  };
+
+  return (
+    nonEmptyCmp(info1.name, info2.name) &&
+    nonEmptyCmp(info1.platform, info2.platform) &&
+    nonEmptyCmp(info1.version, info2.version)
+  );
+}
+
 /**
  * @public
  * @deprecated This interface will be made internal in the next major release.
@@ -90,10 +107,7 @@ export class LimitedSizeDocument {
   }
 }
 
-type MakeClientMetadataOptions = Pick<
-  MongoOptions,
-  'appName' | 'driverInfo' | 'additionalDriverInfo'
->;
+type MakeClientMetadataOptions = Pick<MongoOptions, 'appName'>;
 /**
  * From the specs:
  * Implementors SHOULD cumulatively update fields in the following order until the document is under the size limit:
@@ -102,34 +116,28 @@ type MakeClientMetadataOptions = Pick<
  * 3. Omit the `env` document entirely.
  * 4. Truncate `platform`. -- special we do not truncate this field
  */
-export function makeClientMetadata(options: MakeClientMetadataOptions): ClientMetadata {
+export function makeClientMetadata(
+  driverInfoList: DriverInfo[],
+  { appName = '' }: MakeClientMetadataOptions
+): ClientMetadata {
   const metadataDocument = new LimitedSizeDocument(512);
 
-  const { appName = '' } = options;
   // Add app name first, it must be sent
   if (appName.length > 0) {
     const name =
       Buffer.byteLength(appName, 'utf8') <= 128
-        ? options.appName
+        ? appName
         : Buffer.from(appName, 'utf8').subarray(0, 128).toString('utf8');
     metadataDocument.ifItFitsItSits('application', { name });
   }
 
-  const { name = '', version = '', platform = '' } = options.driverInfo;
-
   const driverInfo = {
-    name: name.length > 0 ? `nodejs|${name}` : 'nodejs',
-    version: version.length > 0 ? `${NODE_DRIVER_VERSION}|${version}` : NODE_DRIVER_VERSION
+    name: 'nodejs',
+    version: NODE_DRIVER_VERSION
   };
 
-  if (options.additionalDriverInfo == null) {
-    throw new MongoRuntimeError(
-      'Client options `additionalDriverInfo` must always default to an empty array'
-    );
-  }
-
   // This is where we handle additional driver info added after client construction.
-  for (const { name: n = '', version: v = '' } of options.additionalDriverInfo) {
+  for (const { name: n = '', version: v = '' } of driverInfoList) {
     if (n.length > 0) {
       driverInfo.name = `${driverInfo.name}|${n}`;
     }
@@ -145,13 +153,10 @@ export function makeClientMetadata(options: MakeClientMetadataOptions): ClientMe
   }
 
   let runtimeInfo = getRuntimeInfo();
-  if (platform.length > 0) {
-    runtimeInfo = `${runtimeInfo}|${platform}`;
-  }
-
-  for (const { platform: p = '' } of options.additionalDriverInfo) {
-    if (p.length > 0) {
-      runtimeInfo = `${runtimeInfo}|${p}`;
+  // This is where we handle additional driver info added after client construction.
+  for (const { platform = '' } of driverInfoList) {
+    if (platform.length > 0) {
+      runtimeInfo = `${runtimeInfo}|${platform}`;
     }
   }
 
@@ -210,7 +215,9 @@ async function getContainerMetadata() {
  * Re-add each metadata value.
  * Attempt to add new env container metadata, but keep old data if it does not fit.
  */
-export async function addContainerMetadata(originalMetadata: ClientMetadata) {
+export async function addContainerMetadata(
+  originalMetadata: ClientMetadata
+): Promise<ClientMetadata> {
   const containerMetadata = await getContainerMetadata();
   if (Object.keys(containerMetadata).length === 0) return originalMetadata;
 
@@ -233,7 +240,7 @@ export async function addContainerMetadata(originalMetadata: ClientMetadata) {
     extendedMetadata.ifItFitsItSits('env', extendedEnvMetadata);
   }
 
-  return extendedMetadata.toObject();
+  return extendedMetadata.toObject() as ClientMetadata;
 }
 
 /**
diff --git a/src/connection_string.ts b/src/connection_string.ts
index edb1a6870a1..97b7d4d62cc 100644
--- a/src/connection_string.ts
+++ b/src/connection_string.ts
@@ -5,7 +5,6 @@ import { URLSearchParams } from 'url';
 import type { Document } from './bson';
 import { MongoCredentials } from './cmap/auth/mongo_credentials';
 import { AUTH_MECHS_AUTH_SRC_EXTERNAL, AuthMechanism } from './cmap/auth/providers';
-import { addContainerMetadata, makeClientMetadata } from './cmap/handshake/client_metadata';
 import { Compressor, type CompressorName } from './cmap/wire_protocol/compression';
 import { Encrypter } from './encrypter';
 import {
@@ -535,16 +534,6 @@ export function parseOptions(
     }
   );
 
-  // Set the default for the additional driver info.
-  mongoOptions.additionalDriverInfo = [];
-
-  mongoOptions.metadata = makeClientMetadata(mongoOptions);
-
-  mongoOptions.extendedMetadata = addContainerMetadata(mongoOptions.metadata).then(
-    undefined,
-    squashError
-  ); // rejections will be handled later
-
   return mongoOptions;
 }
 
diff --git a/src/mongo_client.ts b/src/mongo_client.ts
index 1ff310822db..3f91b6e60ae 100644
--- a/src/mongo_client.ts
+++ b/src/mongo_client.ts
@@ -18,6 +18,7 @@ import type { Connection } from './cmap/connection';
 import {
   addContainerMetadata,
   type ClientMetadata,
+  isDriverInfoEqual,
   makeClientMetadata
 } from './cmap/handshake/client_metadata';
 import type { CompressorName } from './cmap/wire_protocol/compression';
@@ -430,12 +431,16 @@ export class MongoClient extends TypedEventEmitter<MongoClientEvents> implements
       | 'extendedMetadata'
     >;
 
+  private driverInfoList: DriverInfo[] = [];
+
   constructor(url: string, options?: MongoClientOptions) {
     super();
     this.on('error', noop);
 
     this.options = parseOptions(url, this, options);
 
+    this.appendMetadata(this.options.driverInfo);
+
     const shouldSetLogger = Object.values(this.options.mongoLoggerOptions.componentSeverities).some(
       value => value !== SeverityLevel.OFF
     );
@@ -492,8 +497,13 @@ export class MongoClient extends TypedEventEmitter<MongoClientEvents> implements
    * @param driverInfo - Information about the application or library.
    */
   appendMetadata(driverInfo: DriverInfo) {
-    this.options.additionalDriverInfo.push(driverInfo);
-    this.options.metadata = makeClientMetadata(this.options);
+    const isDuplicateDriverInfo = this.driverInfoList.some(info =>
+      isDriverInfoEqual(info, driverInfo)
+    );
+    if (isDuplicateDriverInfo) return;
+
+    this.driverInfoList.push(driverInfo);
+    this.options.metadata = makeClientMetadata(this.driverInfoList, this.options);
     this.options.extendedMetadata = addContainerMetadata(this.options.metadata)
       .then(undefined, squashError)
       .then(result => result ?? {}); // ensure Promise<Document>
diff --git a/test/integration/connection-monitoring-and-pooling/connection.test.ts b/test/integration/connection-monitoring-and-pooling/connection.test.ts
index 7dfbe2be535..eb6a8b39821 100644
--- a/test/integration/connection-monitoring-and-pooling/connection.test.ts
+++ b/test/integration/connection-monitoring-and-pooling/connection.test.ts
@@ -49,10 +49,8 @@ describe('Connection', function () {
           ...commonConnectOptions,
           connectionType: Connection,
           ...this.configuration.options,
-          metadata: makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] }),
-          extendedMetadata: addContainerMetadata(
-            makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] })
-          )
+          metadata: makeClientMetadata([], {}),
+          extendedMetadata: addContainerMetadata(makeClientMetadata([], {}))
         };
 
         let conn;
@@ -74,10 +72,8 @@ describe('Connection', function () {
           connectionType: Connection,
           ...this.configuration.options,
           monitorCommands: true,
-          metadata: makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] }),
-          extendedMetadata: addContainerMetadata(
-            makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] })
-          )
+          metadata: makeClientMetadata([], {}),
+          extendedMetadata: addContainerMetadata(makeClientMetadata([], {}))
         };
 
         let conn;
@@ -108,10 +104,8 @@ describe('Connection', function () {
           connectionType: Connection,
           ...this.configuration.options,
           monitorCommands: true,
-          metadata: makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] }),
-          extendedMetadata: addContainerMetadata(
-            makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] })
-          )
+          metadata: makeClientMetadata([], {}),
+          extendedMetadata: addContainerMetadata(makeClientMetadata([], {}))
         };
 
         let conn;
diff --git a/test/integration/mongodb-handshake/mongodb-handshake.prose.test.ts b/test/integration/mongodb-handshake/mongodb-handshake.prose.test.ts
index da5b98227be..be5e51645ee 100644
--- a/test/integration/mongodb-handshake/mongodb-handshake.prose.test.ts
+++ b/test/integration/mongodb-handshake/mongodb-handshake.prose.test.ts
@@ -1,10 +1,13 @@
 import { expect } from 'chai';
 import * as sinon from 'sinon';
 
+import { type ClientMetadata, type DriverInfo } from '../../../mongodb';
+import { MongoClient as RawMongoClient } from '../../../src';
 import {
   Connection,
   getFAASEnv,
   Int32,
+  isDriverInfoEqual,
   LEGACY_HELLO_COMMAND,
   type MongoClient
 } from '../../mongodb';
@@ -358,4 +361,593 @@ describe('Client Metadata Update Prose Tests', function () {
       });
     }
   });
+
+  describe('Test 3: Multiple Successive Metadata Updates with Duplicate Data', function () {
+    const originalDriverInfo = { name: 'library', version: '1.2', platform: 'Library Platform' };
+    let initialClientMetadata: ClientMetadata;
+    let updatedClientMetadata: ClientMetadata;
+
+    // TODO(NODE-6599): mongodb-legacy adds additional client metadata, breaking these prose tests
+    let client: RawMongoClient;
+
+    // | Case | Name      | Version | Platform           |
+    // | ---- | --------- | ------- | ------------------ |
+    // | 1    | library   | 1.2     | Library Platform   |
+    // | 2    | framework | 1.2     | Library Platform   |
+    // | 3    | library   | 2.0     | Library Platform   |
+    // | 4    | library   | 1.2     | Framework Platform |
+    // | 5    | framework | 2.0     | Library Platform   |
+    // | 6    | framework | 1.2     | Framework Platform |
+    // | 7    | library   | 2.0     | Framework Platform |
+    const tests = [
+      { testCase: 1, name: 'library', version: '1.2', platform: 'Library Platform' },
+      { testCase: 2, name: 'framework', version: '1.2', platform: 'Library Platform' },
+      { testCase: 3, name: 'library', version: '2.0', platform: 'Library Platform' },
+      { testCase: 4, name: 'library', version: '1.2', platform: 'Framework Platform' },
+      { testCase: 5, name: 'framework', version: '2.0', platform: 'Library Platform' },
+      { testCase: 6, name: 'framework', version: '1.2', platform: 'Framework Platform' },
+      { testCase: 7, name: 'library', version: '2.0', platform: 'Framework Platform' }
+    ];
+
+    for (const { testCase, ...driverInfo } of tests) {
+      context(`Case ${testCase}: ${JSON.stringify(driverInfo)}`, function () {
+        // 1. Create a `MongoClient` instance with:
+        //     - `maxIdleTimeMS` set to `1ms`
+        // 2. Append the following `DriverInfoOptions` to the `MongoClient` metadata:
+        //     | Field    | Value            |
+        //     | -------- | ---------------- |
+        //     | name     | library          |
+        //     | version  | 1.2              |
+        //     | platform | Library Platform |
+        // 3. Send a `ping` command to the server and verify that the command succeeds.
+        // 4. Save intercepted `client` document as `updatedClientMetadata`.
+        // 5. Wait 5ms for the connection to become idle.
+        beforeEach(async function () {
+          client = new RawMongoClient(this.configuration.url(), {
+            maxIdleTimeMS: 1,
+            serverApi: this.configuration.serverApi
+          });
+          client.appendMetadata(originalDriverInfo);
+
+          sinon
+            .stub(Connection.prototype, 'command')
+            .callsFake(async function (ns, cmd, options, responseType) {
+              // @ts-expect-error: sinon will place wrappedMethod on the command method.
+              const command = Connection.prototype.command.wrappedMethod.bind(this);
+
+              if (cmd.hello || cmd[LEGACY_HELLO_COMMAND]) {
+                if (!initialClientMetadata) {
+                  initialClientMetadata = cmd.client;
+                } else {
+                  updatedClientMetadata = cmd.client;
+                }
+              }
+              return command(ns, cmd, options, responseType);
+            });
+
+          await client.db('test').command({ ping: 1 });
+          await sleep(5);
+        });
+
+        afterEach(async function () {
+          await client.close();
+        });
+
+        it('metadata is updated correctly, if necessary', async function () {
+          // 1. Append the `DriverInfoOptions` from the selected test case to the `MongoClient` metadata.
+          client.appendMetadata(driverInfo);
+
+          // 2. Send a `ping` command to the server and verify:
+          //     - The command succeeds.
+          await client.db('test').command({ ping: 1 });
+
+          // - The framework metadata is appended to the existing `DriverInfoOptions` in the `client.driver` fields of the `hello`
+          //     command, with values separated by a pipe `|`.  To simplify assertions in these tests, strip out the default driver info
+          //     that is automatically added by the driver (ex: `metadata.name.split('|').slice(1).join('|')`).
+
+          // - If the test case's DriverInfo is identical to the driver info from setup step 2 (test case 1):
+          //     - Assert metadata.name is equal to `library`
+          //     - Assert metadata.version is equal to `1.2`
+          //     - Assert metadata.platform is equal to `LibraryPlatform`
+          // - Otherwise:
+          //     - Assert metadata.name is equal to `library|<name>`
+          //     - Assert metadata.version is equal to `1.2|<version>`
+          //     - Assert metadata.platform is equal to `LibraryPlatform|<platform>`
+          const { driver, platform, ...updatedRest } = updatedClientMetadata;
+          const { driver: _driver, platform: _platform, ...originalRest } = initialClientMetadata;
+
+          const extractParts = (s: string) => s.split('|').slice(1).join('|');
+
+          const actual = {
+            name: extractParts(driver.name),
+            version: extractParts(driver.version),
+            platform: extractParts(platform)
+          };
+
+          const expected = isDriverInfoEqual(driverInfo, originalDriverInfo)
+            ? originalDriverInfo
+            : {
+                name: `library|${driverInfo.name}`,
+                platform: `Library Platform|${driverInfo.platform}`,
+                version: `1.2|${driverInfo.version}`
+              };
+
+          expect(actual).to.deep.equal(expected);
+
+          // All other subfields in the `client` document remain unchanged from `updatedClientMetadata`.
+          expect(updatedRest).to.deep.equal(originalRest);
+        });
+      });
+    }
+  });
+
+  describe('Test 4: Multiple Metadata Updates with Duplicate Data', function () {
+    let initialClientMetadata: ClientMetadata;
+    let updatedClientMetadata: ClientMetadata;
+    // TODO(NODE-6599): mongodb-legacy adds additional client metadata, breaking these prose tests
+    let client: RawMongoClient;
+
+    afterEach(async function () {
+      await client.close();
+    });
+
+    it('does not append duplicate metdata', async function () {
+      // 1. Create a `MongoClient` instance with:
+      //     - `maxIdleTimeMS` set to `1ms`
+
+      client = new RawMongoClient(this.configuration.url(), {
+        maxIdleTimeMS: 1,
+        serverApi: this.configuration.serverApi
+      });
+      // 2. Append the following `DriverInfoOptions` to the `MongoClient` metadata:
+      //   | Field    | Value            |
+      //   | -------- | ---------------- |
+      //   | name     | library          |
+      //   | version  | 1.2              |
+      //   | platform | Library Platform |
+
+      client.appendMetadata({
+        name: 'library',
+        version: '1.2',
+        platform: 'Library Platform'
+      });
+
+      // 3. Send a `ping` command to the server and verify that the command succeeds.
+      await client.db('test').command({ ping: 1 });
+
+      // 4. Wait 5ms for the connection to become idle.
+      await sleep(5);
+
+      // 5. Append the following `DriverInfoOptions` to the `MongoClient` metadata:
+      //   | Field    | Value              |
+      //   | -------- | ------------------ |
+      //   | name     | framework          |
+      //   | version  | 2.0                |
+      //   | platform | Framework Platform |
+      client.appendMetadata({
+        name: 'framework',
+        version: '2.0',
+        platform: 'Framework Platform'
+      });
+
+      // 6. Send a `ping` command to the server and verify that the command succeeds.
+      // 7. Save intercepted `client` document as `clientMetadata`.
+      // 11. Save intercepted `client` document as `updatedClientMetadata`.
+      sinon
+        .stub(Connection.prototype, 'command')
+        .callsFake(async function (ns, cmd, options, responseType) {
+          // @ts-expect-error: sinon will place wrappedMethod on the command method.
+          const command = Connection.prototype.command.wrappedMethod.bind(this);
+
+          if (cmd.hello || cmd[LEGACY_HELLO_COMMAND]) {
+            if (!initialClientMetadata) {
+              initialClientMetadata = cmd.client;
+            } else {
+              updatedClientMetadata = cmd.client;
+            }
+          }
+          return command(ns, cmd, options, responseType);
+        });
+
+      await client.db('test').command({ ping: 1 });
+
+      // 8. Wait 5ms for the connection to become idle.
+      await sleep(5);
+
+      // 9. Append the following `DriverInfoOptions` to the `MongoClient` metadata:
+      //     | Field    | Value            |
+      //     | -------- | ---------------- |
+      //     | name     | library          |
+      //     | version  | 1.2              |
+      //     | platform | Library Platform |
+      client.appendMetadata({
+        name: 'library',
+        version: '1.2',
+        platform: 'Library Platform'
+      });
+
+      // 10. Send a `ping` command to the server and verify that the command succeeds.
+      await client.db('test').command({ ping: 1 });
+
+      // 12. Assert that `clientMetadata` is identical to `updatedClientMetadata`.
+      expect(updatedClientMetadata).to.deep.equal(initialClientMetadata);
+    });
+  });
+
+  describe('Test 5: Metadata is not appended if identical to initial metadata', function () {
+    let initialClientMetadata: ClientMetadata;
+    let updatedClientMetadata: ClientMetadata;
+    // TODO(NODE-6599): mongodb-legacy adds additional client metadata, breaking these prose tests
+    let client: RawMongoClient;
+
+    // 1. Create a `MongoClient` instance with the following:
+    //     - `maxIdleTimeMS` set to `1ms`
+    //     - Wrapping library metadata:
+    //         | Field    | Value            |
+    //         | -------- | ---------------- |
+    //         | name     | library          |
+    //         | version  | 1.2              |
+    //         | platform | Library Platform |
+    // 2. Send a `ping` command to the server and verify that the command succeeds.
+    // 3. Save intercepted `client` document as `initialClientMetadata`.
+    // 4. Wait 5ms for the connection to become idle.
+    beforeEach(async function () {
+      // 1. Create a `MongoClient` instance with:
+      //     - `maxIdleTimeMS` set to `1ms`
+      //     - `driverInfo` set to the following:
+      //     | Field    | Value            |
+      //     | -------- | ---------------- |
+      //     | name     | library          |
+      //     | version  | 1.2              |
+      //     | platform | Library Platform |
+      client = new RawMongoClient(this.configuration.url(), {
+        maxIdleTimeMS: 1,
+        serverApi: this.configuration.serverApi,
+        driverInfo: { name: 'library', version: '1.2', platform: 'Library Platform' }
+      });
+
+      // 2. Send a `ping` command to the server and verify that the command succeeds.
+      // 3. Save intercepted `client` document as `clientMetadata`.
+      sinon
+        .stub(Connection.prototype, 'command')
+        .callsFake(async function (ns, cmd, options, responseType) {
+          // @ts-expect-error: sinon will place wrappedMethod on the command method.
+          const command = Connection.prototype.command.wrappedMethod.bind(this);
+
+          if (cmd.hello || cmd[LEGACY_HELLO_COMMAND]) {
+            if (!initialClientMetadata) {
+              initialClientMetadata = cmd.client;
+            } else {
+              updatedClientMetadata = cmd.client;
+            }
+          }
+          return command(ns, cmd, options, responseType);
+        });
+
+      await client.db('test').command({ ping: 1 });
+
+      // 4. Wait 5ms for the connection to become idle.
+      await sleep(5);
+    });
+
+    afterEach(async function () {
+      await client.close();
+    });
+
+    it('does not append the duplicate metadata', async function () {
+      // 5. Append the following `DriverInfoOptions` to the `MongoClient` metadata:
+      //     | Field    | Value            |
+      //     | -------- | ---------------- |
+      //     | name     | library          |
+      //     | version  | 1.2              |
+      //     | platform | Library Platform |
+      client.appendMetadata({ name: 'library', version: '1.2', platform: 'Library Platform' });
+
+      // 6. Send a `ping` command to the server and verify that the command succeeds.
+      // 7. Save intercepted `client` document as `updatedClientMetadata`.
+      await client.db('test').command({ ping: 1 });
+
+      // 8. Assert that `clientMetadata` is identical to `updatedClientMetadata`.
+      expect(initialClientMetadata).to.deep.equal(updatedClientMetadata);
+    });
+  });
+
+  describe('Test 6: Metadata is not appended if identical to initial metadata (separated by non-identical metadata)', function () {
+    let clientMetadata: ClientMetadata;
+    let updatedClientMetadata: ClientMetadata;
+    // TODO(NODE-6599): mongodb-legacy adds additional client metadata, breaking these prose tests
+    let client: RawMongoClient;
+
+    afterEach(async function () {
+      await client.close();
+    });
+
+    it('does not append duplicate metdaata', async function () {
+      // 1. Create a `MongoClient` instance with:
+      //     - `maxIdleTimeMS` set to `1ms`
+      //     - `driverInfo` set to the following:
+      //     | Field    | Value            |
+      //     | -------- | ---------------- |
+      //     | name     | library          |
+      //     | version  | 1.2              |
+      //     | platform | Library Platform |
+
+      client = new RawMongoClient(this.configuration.url(), {
+        maxIdleTimeMS: 1,
+        driverInfo: {
+          name: 'library',
+          version: '1.2',
+          platform: 'Library Platform'
+        },
+        serverApi: this.configuration.serverApi
+      });
+
+      // 2. Send a `ping` command to the server and verify that the command succeeds.
+      await client.db('test').command({ ping: 1 });
+
+      // 3. Wait 5ms for the connection to become idle.
+      await sleep(5);
+
+      // 4. Append the following `DriverInfoOptions` to the `MongoClient` metadata:
+      //   | Field    | Value              |
+      //   | -------- | ------------------ |
+      //   | name     | framework          |
+      //   | version  | 2.0                |
+      //   | platform | Framework Platform |
+      client.appendMetadata({
+        name: 'framework',
+        version: '2.0',
+        platform: 'Framework Platform'
+      });
+
+      // 5. Send a `ping` command to the server and verify that the command succeeds.
+      // 6. Save intercepted `client` document as `clientMetadata`.
+      // 10. Save intercepted `client` document as `updatedClientMetadata`.
+      sinon
+        .stub(Connection.prototype, 'command')
+        .callsFake(async function (ns, cmd, options, responseType) {
+          // @ts-expect-error: sinon will place wrappedMethod on the command method.
+          const command = Connection.prototype.command.wrappedMethod.bind(this);
+
+          if (cmd.hello || cmd[LEGACY_HELLO_COMMAND]) {
+            if (!clientMetadata) {
+              clientMetadata = cmd.client;
+            } else {
+              updatedClientMetadata = cmd.client;
+            }
+          }
+          return command(ns, cmd, options, responseType);
+        });
+
+      await client.db('test').command({ ping: 1 });
+
+      // 7. Wait 5ms for the connection to become idle.
+      await sleep(5);
+
+      // 8. Append the following `DriverInfoOptions` to the `MongoClient` metadata:
+      //     | Field    | Value            |
+      //     | -------- | ---------------- |
+      //     | name     | library          |
+      //     | version  | 1.2              |
+      //     | platform | Library Platform |
+      client.appendMetadata({
+        name: 'library',
+        version: '1.2',
+        platform: 'Library Platform'
+      });
+
+      // 9. Send a `ping` command to the server and verify that the command succeeds.
+      await client.db('test').command({ ping: 1 });
+
+      // 11. Assert that `clientMetadata` is identical to `updatedClientMetadata`.
+      expect(updatedClientMetadata).to.deep.equal(clientMetadata);
+    });
+  });
+
+  describe('Test 7: Empty strings are considered unset when appending duplicate metadata', function () {
+    let initialClientMetadata: ClientMetadata;
+    let updatedClientMetadata: ClientMetadata;
+    // TODO(NODE-6599): mongodb-legacy adds additional client metadata, breaking these prose tests
+    let client: RawMongoClient;
+
+    afterEach(async function () {
+      await client.close();
+      initialClientMetadata = undefined;
+      updatedClientMetadata = undefined;
+    });
+
+    const driverInfos: Array<{
+      initial: DriverInfo;
+      appended: DriverInfo;
+    }> = [
+      {
+        initial: {
+          name: undefined,
+          version: '1.2',
+          platform: 'Library Platform'
+        },
+        appended: {
+          name: '',
+          version: '1.2',
+          platform: 'Library Platform'
+        }
+      },
+      {
+        initial: {
+          name: 'library',
+          version: undefined,
+          platform: 'Library Platform'
+        },
+        appended: {
+          name: 'library',
+          version: '',
+          platform: 'Library Platform'
+        }
+      },
+      {
+        initial: {
+          name: 'library',
+          version: '1.2',
+          platform: undefined
+        },
+        appended: {
+          name: 'library',
+          version: '1.2',
+          platform: ''
+        }
+      }
+    ];
+
+    for (const [metadata, index] of driverInfos.map((infos, i) => [infos, i] as const)) {
+      describe(`Test ${index + 1}`, function () {
+        it('does not appended duplicate metadata', async function () {
+          // 1. Create a `MongoClient` instance with:
+          // - `maxIdleTimeMS` set to `1ms`
+          client = new RawMongoClient(this.configuration.url(), {
+            maxIdleTimeMS: 1,
+            serverApi: this.configuration.serverApi
+          });
+
+          // 2. Append the `DriverInfoOptions` from the selected test case from the initial metadata section.
+          client.appendMetadata(metadata.initial);
+
+          // 3. Send a `ping` command to the server and verify that the command succeeds.
+          // 4. Save intercepted `client` document as `initialClientMetadata`.
+          // 8. Store the response as `updatedClientMetadata`.
+          sinon
+            .stub(Connection.prototype, 'command')
+            .callsFake(async function (ns, cmd, options, responseType) {
+              // @ts-expect-error: sinon will place wrappedMethod on the command method.
+              const command = Connection.prototype.command.wrappedMethod.bind(this);
+
+              if (cmd.hello || cmd[LEGACY_HELLO_COMMAND]) {
+                if (!initialClientMetadata) {
+                  initialClientMetadata = cmd.client;
+                } else {
+                  updatedClientMetadata = cmd.client;
+                }
+              }
+              return command(ns, cmd, options, responseType);
+            });
+
+          await client.db('test').command({ ping: 1 });
+
+          // 5. Wait 5ms for the connection to become idle.
+          await sleep(5);
+
+          // 6. Append the `DriverInfoOptions` from the selected test case from the appended metadata section.
+          client.appendMetadata(metadata.appended);
+
+          // 7. Send a `ping` command to the server and verify the command succeeds.
+          await client.db('test').command({ ping: 1 });
+
+          // 9. Assert that `initialClientMetadata` is identical to `updatedClientMetadata`.
+          expect(updatedClientMetadata).to.deep.equal(initialClientMetadata);
+        });
+      });
+    }
+  });
+
+  describe('Test 8: Empty strings are considered unset when appending metadata identical to initial metadata', function () {
+    let initialClientMetadata: ClientMetadata;
+    let updatedClientMetadata: ClientMetadata;
+    // TODO(NODE-6599): mongodb-legacy adds additional client metadata, breaking these prose tests
+    let client: RawMongoClient;
+
+    afterEach(async function () {
+      await client.close();
+      initialClientMetadata = undefined;
+      updatedClientMetadata = undefined;
+    });
+
+    const driverInfos: Array<{
+      initial: DriverInfo;
+      appended: DriverInfo;
+    }> = [
+      {
+        initial: {
+          name: undefined,
+          version: '1.2',
+          platform: 'Library Platform'
+        },
+        appended: {
+          name: '',
+          version: '1.2',
+          platform: 'Library Platform'
+        }
+      },
+      {
+        initial: {
+          name: 'library',
+          version: undefined,
+          platform: 'Library Platform'
+        },
+        appended: {
+          name: 'library',
+          version: '',
+          platform: 'Library Platform'
+        }
+      },
+      {
+        initial: {
+          name: 'library',
+          version: '1.2',
+          platform: undefined
+        },
+        appended: {
+          name: 'library',
+          version: '1.2',
+          platform: ''
+        }
+      }
+    ];
+
+    for (const [metadata, index] of driverInfos.map((infos, i) => [infos, i] as const)) {
+      describe(`Test ${index + 1}`, function () {
+        it('does not appended duplicate metadata', async function () {
+          // 1. Create a `MongoClient` instance with:
+          //   - `maxIdleTimeMS` set to `1ms`
+          //   - `driverInfo` set to the `DriverInfoOptions` from the selected test case from the initial metadata section.
+          client = new RawMongoClient(this.configuration.url(), {
+            maxIdleTimeMS: 1,
+            serverApi: this.configuration.serverApi,
+            driverInfo: metadata.initial
+          });
+
+          // 2. Send a `ping` command to the server and verify that the command succeeds.
+          // 3. Save intercepted `client` document as `initialClientMetadata`.
+          // 7. Store the response as `updatedClientMetadata`.
+          sinon
+            .stub(Connection.prototype, 'command')
+            .callsFake(async function (ns, cmd, options, responseType) {
+              // @ts-expect-error: sinon will place wrappedMethod on the command method.
+              const command = Connection.prototype.command.wrappedMethod.bind(this);
+
+              if (cmd.hello || cmd[LEGACY_HELLO_COMMAND]) {
+                if (!initialClientMetadata) {
+                  initialClientMetadata = cmd.client;
+                } else {
+                  updatedClientMetadata = cmd.client;
+                }
+              }
+              return command(ns, cmd, options, responseType);
+            });
+
+          await client.db('test').command({ ping: 1 });
+
+          // 4. Wait 5ms for the connection to become idle.
+          await sleep(5);
+
+          // 5. Append the `DriverInfoOptions` from the selected test case from the appended metadata section.
+          client.appendMetadata(metadata.appended);
+
+          // 6. Send a `ping` command to the server and verify the command succeeds.
+          await client.db('test').command({ ping: 1 });
+
+          // 8. Assert that `initialClientMetadata` is identical to `updatedClientMetadata`.
+          expect(updatedClientMetadata).to.deep.equal(initialClientMetadata);
+        });
+      });
+    }
+  });
 });
diff --git a/test/tools/runner/filters/api_version_filter.ts b/test/tools/runner/filters/api_version_filter.ts
index dcc8b345916..0c4b376ef17 100755
--- a/test/tools/runner/filters/api_version_filter.ts
+++ b/test/tools/runner/filters/api_version_filter.ts
@@ -1,3 +1,4 @@
+import { type MongoClient } from '../../../mongodb';
 import { Filter } from './filter';
 
 /**
@@ -17,7 +18,18 @@ export class ApiVersionFilter extends Filter {
   constructor() {
     super();
     // Get environmental variables that are known
-    this.apiVersion = process.env.MONGODB_API_VERSION;
+    this.apiVersion =
+      typeof process.env.MONGODB_API_VERSION === 'string' &&
+      process.env.MONGODB_API_VERSION.length > 0
+        ? process.env.MONGODB_API_VERSION
+        : undefined;
+  }
+
+  override async initializeFilter(
+    _client: MongoClient,
+    context: Record<string, any>
+  ): Promise<void> {
+    context.serverApi = this.apiVersion;
   }
 
   filter(test: { metadata?: MongoDBMetadataUI }) {
diff --git a/test/tools/runner/hooks/configuration.ts b/test/tools/runner/hooks/configuration.ts
index 1e20f558cad..4f9522e5222 100644
--- a/test/tools/runner/hooks/configuration.ts
+++ b/test/tools/runner/hooks/configuration.ts
@@ -40,7 +40,6 @@ process.env.MONGODB_URI =
 //  determine the connection string based on the value of process.env.AUTH
 const MONGODB_URI = process.env.MONGODB_URI;
 
-const MONGODB_API_VERSION = process.env.MONGODB_API_VERSION;
 // Load balancer fronting 1 mongos.
 const SINGLE_MONGOS_LB_URI = process.env.SINGLE_MONGOS_LB_URI;
 // Load balancer fronting 2 mongoses.
@@ -126,10 +125,6 @@ const testConfigBeforeHook = async function () {
 
   const context = await initializeFilters(client);
 
-  if (MONGODB_API_VERSION) {
-    context.serverApi = MONGODB_API_VERSION;
-  }
-
   if (SINGLE_MONGOS_LB_URI && MULTI_MONGOS_LB_URI) {
     context.singleMongosLoadBalancerUri = SINGLE_MONGOS_LB_URI;
     context.multiMongosLoadBalancerUri = MULTI_MONGOS_LB_URI;
@@ -167,7 +162,7 @@ const testConfigBeforeHook = async function () {
     },
     cryptSharedVersion: context.cryptSharedVersion,
     cryptSharedLibPath: process.env.CRYPT_SHARED_LIB_PATH,
-    serverApi: MONGODB_API_VERSION,
+    serverApi: process.env.MONGODB_API_VERSION,
     atlas: process.env.ATLAS_CONNECTIVITY != null,
     aws: MONGODB_URI.includes('authMechanism=MONGODB-AWS'),
     awsSdk: process.env.MONGODB_AWS_SDK,
diff --git a/test/unit/cmap/handshake/client_metadata.test.ts b/test/unit/cmap/handshake/client_metadata.test.ts
index 8829c9ef981..0ca413f4fdf 100644
--- a/test/unit/cmap/handshake/client_metadata.test.ts
+++ b/test/unit/cmap/handshake/client_metadata.test.ts
@@ -142,7 +142,7 @@ describe('client metadata module', () => {
   describe('makeClientMetadata()', () => {
     context('when no FAAS environment is detected', () => {
       it('does not append FAAS metadata', () => {
-        const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+        const metadata = makeClientMetadata([], {});
         expect(metadata).not.to.have.property(
           'env',
           'faas metadata applied in a non-faas environment'
@@ -165,20 +165,14 @@ describe('client metadata module', () => {
 
     context('when driverInfo.platform is provided', () => {
       it('throws an error if driverInfo.platform is too large', () => {
-        expect(() =>
-          makeClientMetadata({
-            driverInfo: { platform: 'a'.repeat(512) },
-            additionalDriverInfo: []
-          })
-        ).to.throw(MongoInvalidArgumentError, /platform/);
+        expect(() => makeClientMetadata([{ platform: 'a'.repeat(512) }], {})).to.throw(
+          MongoInvalidArgumentError,
+          /platform/
+        );
       });
 
       it('appends driverInfo.platform to the platform field', () => {
-        const options = {
-          driverInfo: { platform: 'myPlatform' },
-          additionalDriverInfo: []
-        };
-        const metadata = makeClientMetadata(options);
+        const metadata = makeClientMetadata([{ platform: 'myPlatform' }], {});
         expect(metadata).to.deep.equal({
           driver: {
             name: 'nodejs',
@@ -197,17 +191,14 @@ describe('client metadata module', () => {
 
     context('when driverInfo.name is provided', () => {
       it('throws an error if driverInfo.name is too large', () => {
-        expect(() =>
-          makeClientMetadata({ driverInfo: { name: 'a'.repeat(512) }, additionalDriverInfo: [] })
-        ).to.throw(MongoInvalidArgumentError, /name/);
+        expect(() => makeClientMetadata([{ name: 'a'.repeat(512) }], {})).to.throw(
+          MongoInvalidArgumentError,
+          /name/
+        );
       });
 
       it('appends driverInfo.name to the driver.name field', () => {
-        const options = {
-          driverInfo: { name: 'myName' },
-          additionalDriverInfo: []
-        };
-        const metadata = makeClientMetadata(options);
+        const metadata = makeClientMetadata([{ name: 'myName' }], {});
         expect(metadata).to.deep.equal({
           driver: {
             name: 'nodejs|myName',
@@ -226,17 +217,14 @@ describe('client metadata module', () => {
 
     context('when driverInfo.version is provided', () => {
       it('throws an error if driverInfo.version is too large', () => {
-        expect(() =>
-          makeClientMetadata({ driverInfo: { version: 'a'.repeat(512) }, additionalDriverInfo: [] })
-        ).to.throw(MongoInvalidArgumentError, /version/);
+        expect(() => makeClientMetadata([{ version: 'a'.repeat(512) }], {})).to.throw(
+          MongoInvalidArgumentError,
+          /version/
+        );
       });
 
       it('appends driverInfo.version to the version field', () => {
-        const options = {
-          driverInfo: { version: 'myVersion' },
-          additionalDriverInfo: []
-        };
-        const metadata = makeClientMetadata(options);
+        const metadata = makeClientMetadata([{ version: 'myVersion' }], {});
         expect(metadata).to.deep.equal({
           driver: {
             name: 'nodejs',
@@ -254,7 +242,7 @@ describe('client metadata module', () => {
     });
 
     context('when no custom driverInto is provided', () => {
-      const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+      const metadata = makeClientMetadata([], {});
 
       it('does not append the driver info to the metadata', () => {
         expect(metadata).to.deep.equal({
@@ -280,12 +268,9 @@ describe('client metadata module', () => {
     context('when app name is provided', () => {
       context('when the app name is over 128 bytes', () => {
         const longString = 'a'.repeat(300);
-        const options = {
-          appName: longString,
-          driverInfo: {},
-          additionalDriverInfo: []
-        };
-        const metadata = makeClientMetadata(options);
+        const metadata = makeClientMetadata([], {
+          appName: longString
+        });
 
         it('truncates the application name to <=128 bytes', () => {
           expect(metadata.application?.name).to.be.a('string');
@@ -300,12 +285,9 @@ describe('client metadata module', () => {
         'TODO(NODE-5150): fix appName truncation when multi-byte unicode charaters straddle byte 128',
         () => {
           const longString = '€'.repeat(300);
-          const options = {
-            appName: longString,
-            driverInfo: {},
-            additionalDriverInfo: []
-          };
-          const metadata = makeClientMetadata(options);
+          const metadata = makeClientMetadata([], {
+            appName: longString
+          });
 
           it('truncates the application name to 129 bytes', () => {
             expect(metadata.application?.name).to.be.a('string');
@@ -318,12 +300,9 @@ describe('client metadata module', () => {
       );
 
       context('when the app name is under 128 bytes', () => {
-        const options = {
-          appName: 'myApplication',
-          driverInfo: {},
-          additionalDriverInfo: []
-        };
-        const metadata = makeClientMetadata(options);
+        const metadata = makeClientMetadata([], {
+          appName: 'myApplication'
+        });
 
         it('sets the application name to the value', () => {
           expect(metadata.application?.name).to.equal('myApplication');
@@ -339,40 +318,37 @@ describe('client metadata module', () => {
 
         it('sets platform to Deno', () => {
           globalThis.Deno = { version: { deno: '1.2.3' } };
-          const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+          const metadata = makeClientMetadata([], {});
           expect(metadata.platform).to.equal('Deno v1.2.3, LE');
         });
 
         it('sets platform to Deno with driverInfo.platform', () => {
           globalThis.Deno = { version: { deno: '1.2.3' } };
-          const metadata = makeClientMetadata({
-            driverInfo: { platform: 'myPlatform' },
-            additionalDriverInfo: []
-          });
+          const metadata = makeClientMetadata([{ platform: 'myPlatform' }], {});
           expect(metadata.platform).to.equal('Deno v1.2.3, LE|myPlatform');
         });
 
         it('ignores version if Deno.version.deno is not a string', () => {
           globalThis.Deno = { version: { deno: 1 } };
-          const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+          const metadata = makeClientMetadata([], {});
           expect(metadata.platform).to.equal('Deno v0.0.0-unknown, LE');
         });
 
         it('ignores version if Deno.version does not have a deno property', () => {
           globalThis.Deno = { version: { somethingElse: '1.2.3' } };
-          const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+          const metadata = makeClientMetadata([], {});
           expect(metadata.platform).to.equal('Deno v0.0.0-unknown, LE');
         });
 
         it('ignores version if Deno.version is null', () => {
           globalThis.Deno = { version: null };
-          const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+          const metadata = makeClientMetadata([], {});
           expect(metadata.platform).to.equal('Deno v0.0.0-unknown, LE');
         });
 
         it('ignores version if Deno is nullish', () => {
           globalThis.Deno = null;
-          const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+          const metadata = makeClientMetadata([], {});
           expect(metadata.platform).to.equal('Deno v0.0.0-unknown, LE');
         });
       });
@@ -386,7 +362,7 @@ describe('client metadata module', () => {
           globalThis.Bun = class {
             static version = '1.2.3';
           };
-          const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+          const metadata = makeClientMetadata([], {});
           expect(metadata.platform).to.equal('Bun v1.2.3, LE');
         });
 
@@ -394,10 +370,7 @@ describe('client metadata module', () => {
           globalThis.Bun = class {
             static version = '1.2.3';
           };
-          const metadata = makeClientMetadata({
-            driverInfo: { platform: 'myPlatform' },
-            additionalDriverInfo: []
-          });
+          const metadata = makeClientMetadata([{ platform: 'myPlatform' }], {});
           expect(metadata.platform).to.equal('Bun v1.2.3, LE|myPlatform');
         });
 
@@ -405,7 +378,7 @@ describe('client metadata module', () => {
           globalThis.Bun = class {
             static version = 1;
           };
-          const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+          const metadata = makeClientMetadata([], {});
           expect(metadata.platform).to.equal('Bun v0.0.0-unknown, LE');
         });
 
@@ -413,19 +386,13 @@ describe('client metadata module', () => {
           globalThis.Bun = class {
             static version = 1;
           };
-          const metadata = makeClientMetadata({
-            driverInfo: { platform: 'myPlatform' },
-            additionalDriverInfo: []
-          });
+          const metadata = makeClientMetadata([{ platform: 'myPlatform' }], {});
           expect(metadata.platform).to.equal('Bun v0.0.0-unknown, LE|myPlatform');
         });
 
         it('ignores version if Bun is nullish', () => {
           globalThis.Bun = null;
-          const metadata = makeClientMetadata({
-            driverInfo: { platform: 'myPlatform' },
-            additionalDriverInfo: []
-          });
+          const metadata = makeClientMetadata([{ platform: 'myPlatform' }], {});
           expect(metadata.platform).to.equal('Bun v0.0.0-unknown, LE|myPlatform');
         });
       });
@@ -546,7 +513,7 @@ describe('client metadata module', () => {
           });
 
           it(`returns ${inspect(outcome)} under env property`, () => {
-            const { env } = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+            const { env } = makeClientMetadata([], {});
             expect(env).to.deep.equal(outcome);
           });
 
@@ -570,9 +537,7 @@ describe('client metadata module', () => {
       });
 
       it('does not attach it to the metadata', () => {
-        expect(
-          makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] })
-        ).not.to.have.nested.property('aws.memory_mb');
+        expect(makeClientMetadata([], {})).not.to.have.nested.property('aws.memory_mb');
       });
     });
   });
@@ -587,7 +552,7 @@ describe('client metadata module', () => {
       });
 
       it('only includes env.name', () => {
-        const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+        const metadata = makeClientMetadata([], {});
         expect(metadata).to.not.have.nested.property('env.region');
         expect(metadata).to.have.nested.property('env.name', 'aws.lambda');
         expect(metadata.env).to.have.all.keys('name');
@@ -605,7 +570,7 @@ describe('client metadata module', () => {
         });
 
         it('only includes env.name', () => {
-          const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+          const metadata = makeClientMetadata([], {});
           expect(metadata).to.have.property('env');
           expect(metadata).to.have.nested.property('env.region', 'abc');
           expect(metadata.os).to.have.all.keys('type');
@@ -622,7 +587,7 @@ describe('client metadata module', () => {
         });
 
         it('omits os information', () => {
-          const metadata = makeClientMetadata({ driverInfo: {}, additionalDriverInfo: [] });
+          const metadata = makeClientMetadata([], {});
           expect(metadata).to.not.have.property('os');
         });
       });
@@ -638,10 +603,7 @@ describe('client metadata module', () => {
       });
 
       it('omits the faas env', () => {
-        const metadata = makeClientMetadata({
-          driverInfo: { name: 'a'.repeat(350) },
-          additionalDriverInfo: []
-        });
+        const metadata = makeClientMetadata([{ name: 'a'.repeat(350) }], {});
         expect(metadata).to.not.have.property('env');
       });
     });
diff --git a/test/unit/sdam/topology.test.ts b/test/unit/sdam/topology.test.ts
index 60c4dcf2def..444ff7d3e86 100644
--- a/test/unit/sdam/topology.test.ts
+++ b/test/unit/sdam/topology.test.ts
@@ -53,10 +53,8 @@ describe('Topology (unit)', function () {
 
     it('should correctly pass appname', function () {
       const server: Topology = topologyWithPlaceholderClient([`localhost:27017`], {
-        metadata: makeClientMetadata({
-          appName: 'My application name',
-          driverInfo: {},
-          additionalDriverInfo: []
+        metadata: makeClientMetadata([], {
+          appName: 'My application name'
         })
       });