diff --git a/src/Symfony/Component/Security/Core/Role/RoleHierarchy.php b/src/Symfony/Component/Security/Core/Role/RoleHierarchy.php
index d911fe3dab16e..76a5548d0622d 100644
--- a/src/Symfony/Component/Security/Core/Role/RoleHierarchy.php
+++ b/src/Symfony/Component/Security/Core/Role/RoleHierarchy.php
@@ -48,7 +48,7 @@ public function getReachableRoleNames(array $roles): array
             }
         }
 
-        return $reachableRoles;
+        return array_values(array_unique($reachableRoles));
     }
 
     protected function buildRoleMap()
diff --git a/src/Symfony/Component/Security/Core/Tests/Role/RoleHierarchyTest.php b/src/Symfony/Component/Security/Core/Tests/Role/RoleHierarchyTest.php
index b84889f57a6cd..5c42e0b39f8bf 100644
--- a/src/Symfony/Component/Security/Core/Tests/Role/RoleHierarchyTest.php
+++ b/src/Symfony/Component/Security/Core/Tests/Role/RoleHierarchyTest.php
@@ -28,5 +28,6 @@ public function testGetReachableRoleNames()
         $this->assertEquals(['ROLE_ADMIN', 'ROLE_USER'], $role->getReachableRoleNames(['ROLE_ADMIN']));
         $this->assertEquals(['ROLE_FOO', 'ROLE_ADMIN', 'ROLE_USER'], $role->getReachableRoleNames(['ROLE_FOO', 'ROLE_ADMIN']));
         $this->assertEquals(['ROLE_SUPER_ADMIN', 'ROLE_ADMIN', 'ROLE_FOO', 'ROLE_USER'], $role->getReachableRoleNames(['ROLE_SUPER_ADMIN']));
+        $this->assertEquals(['ROLE_SUPER_ADMIN', 'ROLE_ADMIN', 'ROLE_FOO', 'ROLE_USER'], $role->getReachableRoleNames(['ROLE_SUPER_ADMIN', 'ROLE_SUPER_ADMIN']));
     }
 }