I got twins this year...
I actually watched this teeny tiny little amel hatch from an egg, thinking, "what else is in there taking up all that space?" I then saw another amel through the hole in the egg.
You can see him in there. His eye is the most obvious part.
(I spent most of my free time this week just laying on the floor watching the egg box like a movie, so I saw quite a few of them emerge from the egg... this one worried me, he came out and spazzed when his umbilical cord was still connected. He was thrashing and I actually grabbed a pair of scissors and cut the cord because I was afriad he was gonna screw himself up pulling so hard.)
After they both came out, I checked that egg, and there were no other holes in it. (So it didn't come through another egg.) I also counted the eggs vs hatchlings after all was said and done. Definitely twins.
Their head patterns are amazingly similar, although the rest of the pattern varies a lot between them. However, there's a lot of "aztec-like" influence in pretty much the entire clutch, and that might be a totally randomizing factor on pattern anomolies. (They genetically cloned a calico cat and the "white patch" was different on the clone.
)
So I dunno if they're "identical twins," but it probably doesn't matter. They're both way small, one of them is even smaller and horribly uncoordinated (looks like neurological problems and I bet he won't eat even if he does live for long) and they both have some kinks, probably from "starving" inside the egg as a result of sharing all the food.
BTW I don't think anyone mentioned this, but two-headed snakes (of all kinds of species) are conjoined twins. (I'm pretty sure those are all identical twins, IIRC.)
So it happens. Dunno how often though. I've probably "beaten" the odds...