It's a policy on one of the sites I help manage that spammers and banned users get prefixed with _ in their username, so we know which ones have already been processed and not. I just happen to notice that the spam cleaner log linking to a user doesn't update the changed usernames. So spammer rachel341 renamed to _rachel341 will show as rachel341. I assume this is perhaps because it is a 'log' and the original name was that, and it doesn't pull the current username for that user. But reporting anyway, in case it should do that.