Technically, if they are really identical twins, (not fraternal that look alike) they have the same DNA. They are split from one fertilized ovum. I would imagine that a name difference would in this case be the only legal way to differentiate the two. In cases where the one is being suspected ( later in life) of a crime, paternity, etc. a way of distinguishing them needs to be in order. It's a sticky situation, and body scars, dental work, etc would have to be the determining factors rather than DNA. Weird, huh ? My neices are identical, proven by DNA, and one is a physician. She said technically their children are 1/2 brother and sister rather than cousins, as most sibling's children would be.