I'm not a twin, but I think it's interesting how two offspring canbe produced at the same time. 
Oh yeah. I have known a lot of twins in my life and I find it a pretty cool phenomenon. 
For fraternal twins each twin is fertalized by its own sperm cell. 
Are those the type of twins that don't look alike?
Yup, that's because they have two different combinations of DNA
The Olsen twins are fraternal but they look identical. I find that funny. But it makes sense because a lot of different aged siblings look just alike too.
That is actually refered to as doppelgangers!