I guess you could go through the posts and compare spelling errors, punctuation, grammatical errors that are the same...but in the end, eventually, someone with alternative names will slip up. It might take a long time, but someone can only carry on aliases for so long before they hit the wrong key or something of that nature.
And of course, you could always just ask. But that is like a shot in the dark, and if someone has an alternative name, obviously they have a reason to keep it secret. So...
*sigh*
I guess the whole point of this post is to say I don't know.
Thanks for your replies, I dunno either. I've actually found 1 or 2 of the people I'm getting a problem from, so it's worked out in a way. Some people were signing on here, and getting stuff to blackmail me with....long story...but anyway....You're right on the slip-ups, and unfortunately, checking for grammatical errors and punctuation is a difficult thing to use for determination, as everyone changes those sometimes, and if you really don't know that person, it's even more difficult LoL. Thanks again you all.