diff --git a/cabal-testsuite/PackageTests/ProjectDupPkg/cabal.out b/cabal-testsuite/PackageTests/ProjectDupPkg/cabal.out
new file mode 100644
index 00000000000..3c50b2abdfa
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectDupPkg/cabal.out
@@ -0,0 +1,14 @@
+# checking repl command with a 'cabal.project' and no project options
+# cabal repl
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following will be built:
+ - pkg-one-0.1 (interactive) (first run)
+Configuring pkg-one-0.1...
+Preprocessing library for pkg-one-0.1...
+# checking repl command with the 'all' target
+# cabal repl
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following will be built:
+ - pkg-one-0.1 (interactive) (first run)
+Preprocessing library for pkg-one-0.1...
diff --git a/cabal-testsuite/PackageTests/ProjectDupPkg/cabal.project b/cabal-testsuite/PackageTests/ProjectDupPkg/cabal.project
new file mode 100644
index 00000000000..2f191f96e7e
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectDupPkg/cabal.project
@@ -0,0 +1 @@
+packages: pkg-one, pkg-two
diff --git a/cabal-testsuite/PackageTests/ProjectDupPkg/cabal.test.hs b/cabal-testsuite/PackageTests/ProjectDupPkg/cabal.test.hs
new file mode 100644
index 00000000000..77e6eb308c6
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectDupPkg/cabal.test.hs
@@ -0,0 +1,25 @@
+import Test.Cabal.Prelude
+import Data.List (isInfixOf)
+
+main = cabalTest . recordMode RecordMarked $ do
+  liftIO $ skipIfWindows "I'm seeing extra newlines in the output on Windows"
+  let log = recordHeader . pure
+
+  -- If there is only one package in the project then the target could be inferred.
+  log "checking repl command with a 'cabal.project' and no project options"
+  defaultProject <- cabal' "repl" ["pkg-one"]
+  assertOutputContains "the following will be built" defaultProject
+  assertOutputContains "pkg-one-0.1" defaultProject
+  -- Foo is a module in one of the packages pkg-one-0.1
+  -- assertOutputContains "Compiling Foo" defaultProject
+  assertOutputContains "Compiling Bar" defaultProject
+
+  log "checking repl command with the 'all' target"
+  allTarget <- cabal' "repl" ["all"]
+  assertOutputContains "the following will be built" allTarget
+  assertOutputContains "pkg-one-0.1" allTarget
+  -- Foo is a module in one of the packages pkg-one-0.1
+  -- assertOutputContains "Compiling Foo" allTarget
+  assertOutputContains "Compiling Bar" allTarget
+
+  return ()
diff --git a/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-one/Foo.hs b/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-one/Foo.hs
new file mode 100644
index 00000000000..8a39fe134cf
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-one/Foo.hs
@@ -0,0 +1,4 @@
+module Foo where
+
+a :: Int
+a = 42
diff --git a/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-one/pkg-one.cabal b/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-one/pkg-one.cabal
new file mode 100644
index 00000000000..3e17e5074d7
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-one/pkg-one.cabal
@@ -0,0 +1,9 @@
+name:          pkg-one
+version:       0.1
+license:       BSD3
+cabal-version: >=1.2
+build-type:    Simple
+
+library
+  exposed-modules: Foo
+  build-depends:   base
diff --git a/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-two/Bar.hs b/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-two/Bar.hs
new file mode 100644
index 00000000000..870176c2b2d
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-two/Bar.hs
@@ -0,0 +1,4 @@
+module Bar where
+
+a :: Int
+a = 42
diff --git a/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-two/pkg-one.cabal b/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-two/pkg-one.cabal
new file mode 100644
index 00000000000..5708318ba15
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ProjectDupPkg/pkg-two/pkg-one.cabal
@@ -0,0 +1,9 @@
+name:          pkg-one
+version:       0.1
+license:       BSD3
+cabal-version: >=1.2
+build-type:    Simple
+
+library
+  exposed-modules: Bar
+  build-depends:   base