I recently managed to do that as well. This becomes very interesting if you try to recover a password, because apparently the password recovery only recovers the last account.

Eventually I got out of that by changing the mail of whatever account I could log into, using gmails feature of ignoring everything between the first + and an @ in the address. But most annoying, now my aws login is something silly like [email protected].

Maybe I could change that back, but I'm too scared to touch that.