DS had identical twins in his K class and no one could tell them apart. DS never knew which one he was talking to and probably addressed them as the wrong name 50 percent of the time. I can see how that can cause big identity issues in a child.
It sounds like it would be a good idea to put them together in this case--but make them look as different as possible. These twins had their hair and everything the same.
This year they are separated and DS has one of them in his class. Not sure if that was the parents' idea or the school's.