Symfony 4 / MongoDB / Docker multiple entries when saving data

I’m using Symfony 4 and MongoDB with docker and i want to save a new document (only one) on my database but multiple entries are inserted.

.env file :

PROJECT_DIR=/var/www/movies
APACHE_PORT=8080
PHP_PORT=9000
MONGODB_USER=test
MONGODB_PASSWORD=test
MONGODB_HOST=mongo
MONGODB_PORT=27017
MONGODB_DB=movies

MONGODB_URL=mongodb://${MONGODB_HOST}:${MONGODB_PORT}

doctrine_mongodb.yaml:

doctrine_mongodb:
    auto_generate_proxy_classes: true
    auto_generate_hydrator_classes: true
    connections:
        default:
            server: '%env(resolve:MONGODB_URL)%'
            options:
                username: '%env(resolve:MONGODB_USER)%'
                password: '%env(resolve:MONGODB_PASSWORD)%'
    default_database: '%env(resolve:MONGODB_DB)%'
    document_managers:
        default:
            auto_mapping: true
            mappings:
                App:
                    is_bundle: false
                    type: annotation
                    dir: '%kernel.project_dir%/src/Document'
                    prefix: 'AppDocument'
                    alias: App

Controller index function:

 /**
     * @Route("/", name="base")
     */
    public function index(DocumentManager $dm)
    {
        $movie = new Movie();
        $movie->setTitle("Test");
        $dm->persist($movie);
        $dm->flush();

        return $this->render('base/index.html.twig');
    }

Source: StackOverflow