How to get her to stop copying me?

Wow! This is sooo creepy. Two of my BFFs are exactly like this. They used to be best friends, but now they hate each other. I think its really sad b/c they were so close. Anyway you should just tell her to get her own life(in a nicer way if possible) You should help her to find her own identity. But if you really hate this girl, just stop talking to her. I would go with the first option. Soul searching could be fun.