Girl cuts the sides her dress at the very end because another girl was wearing the same black dress?

I don’t remember much about the movie. As I said in the question, I remember that around the end of the movie the girl cuts the sides her dress because another girl was wearing the same black dress? It’s probably some sort of teen movie. Maybe one of those makeover (“ugly” to “beautiful”) movies? I think somewhere in the movie there was some scenes of girls trying to sabotage each other. Don’t remember what but I remember there was a scene where her lips puffed up or something as well. Please help me if you can, it’s been driving me insane trying to remember which movie this is. I would really appreciate your help, thank you.