You should definitely tell your friend.
And just because you say that your friend is "ugly", doesn't mean that other people would think that she's ugly.
Wow, you sound JUST LIKE MY SISTER. Back when I wore a few clothes that were Abercrombie, she would say "Oh, that doesn't look good on you!" or say "OMG, Is that A&F? Ew, BITER!" Biter as in copycat. I just looked at her and said, "You know what? Ew. You don't OWN this label." At least I'm not all decked out in that label. My sister was the total A&F freak and would always look me up and down. o__O"
Anyways, back to this. Honestly, girl, you DON'T OWN the label. If it's so annoying, tell your friend that it bothers you, but you're probably not going to get a very nice answer because she's most likely going to tell you that there are other people with the same clothes. Plus, if I were you, I would feel flattered.
Plus, I think EVERYONE copies others (except maybe original designers themselves) in fashion, in one way or another, even if it's in a subtle way. As for hair, since someone mentioned it, that's similar to fashion because i see many people with similar hairstyles.
Now, PERSONALITY is a different story. Personalities can be copied, but only to a certain extent.
Now THAT is something to gripe about because what if other people start telling you that you're an imitation of the person who is imitating you? Of couse, this thread isn't about personality.

The band sweatshirt - seriously, I bet a bunch of other people have that too. They have a lot of fans and fanclothes are not really exclusive, KTHXBYE.