I have two placentas/sacs and because they got put back at 6 days - highly unlikely to be identical as one egg will only split into two placentas /two sacs under three days. I didn't have ICSI either. After 3 days they have usually one sac/placenta.
Two other IVF twin mums I know an another board have ID twins from one embryo - one was from ICSI one wasn't ...both had 2-3 day transfers though.
Guess I will find out soon enough ... though as brothers they could look very alike anyway.