I also have twins. You don't need to tell them apart because you can just do everything to both of them. There is one boob for each. If you change one, you change the other. The names don't matter; even with my non-twins I just call them "baby" for a year or two. (so "this baby" and "that baby", or "left baby" and "right baby", or "port baby" and "starboard baby")
Soon enough, one will fall down some steps or fall out of a stroller, and then you'll be able to tell them apart by the scar.