Django how to create, update and keep clone objects to another database for backup purpose?

Question

postgresql is my primary data base. If any object create in my original database then I want it will also keep an duplicate object in my secondary database. I read Django documentation for create an clone database but didn't work. here is my code:

#replicarouter.py

 class PrimaryReplicaRouter:
    def db_for_read(self, model, **hints):
        """
        Reads go to a randomly-chosen replica.
        """
        return 'primary'

    def db_for_write(self, model, **hints):
        """
        Writes always go to primary.
        """
        return 'primary'

    def allow_relation(self, obj1,**hints):
        """
        Relations between objects are allowed if both objects are
        in the primary/replica pool.
        """
        db_set = {'primary', 'replica_database'}
        if obj1._state.db in db_set:
            return True
        return None

    def allow_migrate(self, db, app_label, model_name=None, **hints):
        """
        All non-auth models end up in this pool.
        """
        return True
 

settings.py

     DATABASES = {
        'default':{},
        'primary': {
            'ENGINE': 'django.db.backends.postgresql',
            'NAME': 'my_db_name',
            'USER': 'postgres',
            'PASSWORD': 'my_db_pass',
            'HOST': 'localhost',
            'PORT':5432,
        },

        'replica_database': {
            'ENGINE': 'django.db.backends.mysql',
            'NAME': 'my_db_name',
            'USER': 'root',
            'PASSWORD': '',
            'HOST': 'localhost',
            'PORT': 3306,
        }

        
    }

DATABASE_ROUTERS = ['my_root_folder_name.dbrouters.AuthRouter','my_root_folder_name.replicarouter.PrimaryReplicaRouter']

right now all new objects creating in my primary database. I want to keep clone of every new object in my replica_database. If any object added in my primary database then it will also add an clone object in my replica_database.