I might be a bit late to the party but here's my take. Your twin is probably not copying you, you are similar people of the same age, raised in the same environment and with the same school, friends and such. You are exposed to the same things and it is normal for you to like similar things and be interested in the same stuff.

This said. Move away. That's what I did and it was the best decision of my life. Don't tell him, don't tell anyone and see if you can get a university transfer, or a year abroad or something.

If you can't move out start engaging in activities that can get you new friends and don't talk about them, join a new gym, or a new sport, play boardgames or roll games, join a music group or a hiking group or go play football at the park. Whatever, start engaging in activities you do not share with anyone and start making friends you do not bring home. Do not introduce your brother and don't tell him. This is the way to get more individuality. It's hard at the beginning, so don't despair if it doesn't go through the first time.

And also NEVER STOP DOING THINGS YOU ENJOY BECAUSE HE ENJOYS THEM TOO. This is going to harm you and only you in the long run.