Use a spare email address, not your own account. Test 3 asks the website to create a player profile, and the website may record whichever login ran it against that profile. A spare address keeps your real account clean.
Tests 1 and 2 only read. Test 3 creates one test profile and tells you how to delete it afterwards.
Neither of these changes anything.
This is the one that answers the open question: what the website replies when the same login asks about a profile it already owns. It creates one test player called ZZ Diagnostic, then asks about it twice.
Paste this whole thing back into the chat.
Nothing run yet.