There is, I shit you not, a "Retro_" here on GAF. Dunno how that's permissible, to just slap an underscore there, but oh well. I've thought about mentioning it to a moderator, but since this person doesn't try to impersonate me I guess there's no foul play. Strangely enough he registered on my birthday.
There's a few people floating around with "Retro' in their name, but none quite so blatantly similar. There's even a "Retro-lover", but as far as I know he or she has never professed this love directly to me.
There's also a guy named "Kid Dracula" who uses a similar avatar, but he's cool and has good taste so I don't mind.
As far as the internet goes, Retro is pretty common. I have a lot of them, but in a few places I've had to switch back to "Retrogames", which was the original screen name from waaaaay back in the late 90s before people started shortening it to just "Retro". I know there's a Retro on the TIGSource forums, that's the only one I've directly encountered.