My outsider understanding is that the character database has account names, but no other information. So if you remember your login account name and/or your global handle, your characters can be found.
Most of my account names since CoH shut down have been the name of my favorite character, but what my CoH account names was...oh wait...I think I remember.
Ultimately it does not really matter to me if someone else is playing a dupe of one of my characters. That would really be a form of flattery, no?