If you have ended up with two Nettla accounts without wanting to have that, it may be that you logged in with an email the first time, and then with Apple or Google the second time, or vice versa.
If this happens and you want to delete one of them :
Log in to the account that you want to remove -> Go to profile -> Settings -> Scroll down -> Delete account. You can then log in on the account that you want to use.