Abillity to wipe allowed PCIDs

[TESTRETIS]

I've noticed that recently that some people who register a PCID secured account sometimes get linked to other people as well, and if two people happen to login to the same pc (in a public place, or friends house) or a PC that has forged an ID can get into the account if they know the password. When I got an email, accounts I do not own appear allowed for my PCID. Also, I think there should be a random string of letters/numbers/symbols to be used for PCIDs, this would help improve the security in my opinion.