Back when I hunted on a DMAP where ODW biologists were involved in each property, we were told that does in their first, second and maybe their third year would have single fawns. Senior does would have twins, so the recommendation from the biologist was to shoot senior does and leave the young does. It was more typical for younger does to have buck fawns, and senior does to have twin does we were told.
That's the info I gathered. Our buck to doe ratio was 65-1 when we started, and when I left the DMAP it was 42-1. We killed 40 does a year and I was in the program for over 10 years.
As to being fraternal or identical, I'd have to refer to others. I don't have that answer.
Edit: I do know in humans, there is the possibility of two children, not twins by two sires and one doe at a single birth.
Watched Maury Povich a couple of times to prove it.
You are NOT the father!!! (That's your Q to run off the stage while she still claims you are and wants a check from you monthly.)