Fix issue where addSelect may result in duplicate columns being selected. (#46049)

Co-authored-by: Menzo Wijmenga <[email protected]>

Author: vdlp-mw

src/Illuminate/Database/Query/Builder.php

@@ -411,6 +411,10 @@ public function addSelect($column)
 
                 $this->selectSub($column, $as);
             } else {
+                if (is_array($this->columns) && in_array($column, $this->columns, true)) {
+                    continue;
+                }
+
                 $this->columns[] = $column;
             }
         }

tests/Database/DatabaseQueryBuilderTest.php

@@ -107,7 +107,7 @@ public function testAliasWrappingWithSpacesInDatabaseName()
     public function testAddingSelects()
     {
         $builder = $this->getBuilder();
-        $builder->select('foo')->addSelect('bar')->addSelect(['baz', 'boom'])->from('users');
+        $builder->select('foo')->addSelect('bar')->addSelect(['baz', 'boom'])->addSelect('bar')->from('users');
         $this->assertSame('select "foo", "bar", "baz", "boom" from "users"', $builder->toSql());
     }