This was an old problem, many ATT Galaxy S 2 users said the Musicshows聽聽repeatedly聽 duplicate songs after they installed the AOKP ICS ROM on their device, but when they go to check this, physically there are no duplicates soogs. It’s so strange, it seems this is a bug, but Samsung hasn’t offer a software update to solve this problem so far. Fotunately one users shared one method to fix this duplicates issue by doing this: Goto Settings > Apps > Media Storage, select Clear Data, then Reboot.
Because I don’t have the att galaxy s2, I can’t try persoanlly the method. But a few owners said this way worked well on their handset. Hopefully it will also work for you!