Does this girl want my life & is a stalker, or does she just admire me?

[finn]

This insanely gorgeous college girl (way more beautiful than anything I've ever seen) copies literally everything I do; makeup, hair style/color, clothes, interests, etc- you name it. She likes every single one of my facebook photos/statuses I post. Whenever I talk to my fiancee she does this super loud, flirty, high-pitched giggle & frequently asks about him too. She befriends all of my friends, goes to all the same events I go to, copies all my hair/fashion style within the week. But she does these things in almost a subtle way & it's starting to bother me lately. I've known her for 5 years, but only hung out a few times. We never really talk.

I need some advice on how I should handle this, or if I should be flattered? What would you do?
-Thanks