I run the fixtures locally and everything is alright.

On heroku, i run heroku run python manage.py loaddata fixtures.json and it failed

django.db.utils.IntegrityError: Problem installing fixture '/app/fixtures.json': Could not load auth.User(pk=1): duplicate key value violates unique constraint "users_profile_user_id_key"
DETAIL:  Key (user_id)=(1) already exists.

i have logined with admin and delete all users and posts on heroku. what could I do?