this still make it a lot of work for the gm who had to check each name, and also silly names like |-|0m0r $!mp50n - ok maybe some sign would be forbidden that it don't becme that weird but don't underestimate creativity.
What about this, user can suggest non existing first or last names to gm using a system. gm could approve or disapprove (ignore will lead to disapproval). If a name is approved, it will appear in the list and these legal names will appear in this world later either by user's rename action or by the generation system.
Users could rename one draft using the list to create a universal unique (or maxium n players could share a name) name every season.