The primary reason everyone assumes that rabbitscan have double litters is the fact that they have 2 uterinehorns. However, cows, pigs, cats, shrews, horses, dogs, etc.*all* have 2 uterine horns. In humans, it also occurs, but isconsidered a congenital anomaly and those women are prone to miscarry.
Superfoetation can occur in rabbits, it would be very rarethough. I have had an occurance of a healthy setofkits born4 days apart -- but the doe had onlybeen bred once, so I know it was not a separate conception.In some cases, the doe rebreeds to the buck immediately after givingbirth, and some people assume that is a second litter -- however, it'sjust another full term litter with a normal gestation.
I have learned that certainly nothing is impossible. I got tosee a set of conjoined kittens -- one male and one female.This is considered one of those *impossibilities*, however, after muchresearch, I found 4 documented cases in humans of conjoined twins beingof opposite sex. It is due to a chromosome abnormality duringthe development of two male conjoined twins.
Pam