We have two doe rabbits that are sisters and share a cage (10 x 20), a hutch, and have access to a shed (4 x 8 ish). One night, about a month ago, they "escaped" into the space used by our buck. They were still only 4 months old, so we were not sure if they got pregnant. Last week we found 1 nest in the shed, so we thought only 1 of them was pregnant. Yesterday morning we found the nest occupied by 22 bunnies. They both had their litters in the same nest. Not sure how they can tell who's is whose, but I am sure they will figure something out.