Apparently, there's a member named "Mr biz" and another member named "Mr. Biz". The problem here is that both of them end up having a directory named "mr_biz". I encountered this problem while trying to change the `directory_name-parent` key on the `directories` table to a unique key.
Not only does this prevent the unique key from being created, it prevents access to one of the users' profiles. I'll need to figure out some way to work around this problem. (Maybe use "__" for the period instead of "_"?)
Also, registration will have to be updated to check for this type of nick collision.