I hate it when people copy me too.
My best friend a couple of years ago copied me like crazy.
I confronted her about it, but in the wrong way I guess. We had loads of arguements about it.
So erm, I recommend you do it reaallly politely?
Don't get me wrong, this isn't the reason she isn't my best friend anymore. xD I just don't see as much as her since we went to high school.
I know how you feel. Having a clone of you is really annoying, and you just want to be you. But how can you be just you if someone else is being you? Trying not to confuse people D:
Good luck to you, twinsay. <3