Amazon owns IMDB and shares the same automated login system. They are different accounts, so of course you can delete one account without hurting the other. But the process will repeat. IMDb ask, does the user have credentials for an a account? Amazon says, yes, this user has these credentials. IMDB logs your credentials and sees that you don’t have an account, so they kick start a brand new one tied to your already existing credentials and the information they already collected from your usage.

Maybe try a different browser with containers, or accessing in incognito mode. If you already use IMDB so much, they already know most about you. They fingerprint and collect a profile about your usage.

Maybe switch to a different service like TMDB or whatever.