The gestation period for rabbits is 31 days, plus or minus a couple. If your does were with a buck within the last month, one or both could be pregnant. Or, if one doe has been riding the other, the ridden doe could be experiencing a false pregnancy. I second the advice to separate them and give them nest boxes!
It may also be that this has nothing to do with pregnancy, that these girls have just reached a point where they each need their own space. I had a couple of rabbits that I sold, that came back to me when their owners' interest waned (one of the reasons that I
do not do "Easter bunnies!!) According to their owner, these girls were "the best friends in the whole world," and she made me promise to see to it that they went to the same home, together, when I next placed them. Within a month, one doe's "best friend in the whole world" took a piece of skin the size of a postage stamp off her backside! These girls were about 8-9 months old, and neither of them was pregnant.
Certain rabbit rescue groups will tell you that rabbits are social creatures, and need the company of other rabbits. I personally think that the idea of "bonded" rabbits is a load of horse hooey! Some rabbits get along with other rabbits, some don't; IMO it's as simple as that. Many rabbits that were fine together as babies have to be separated once they reach sexual maturity. It sounds as if your girls have gotten to that point.
If either or both of your does
are pregnant, you'd want to be separating them in any case. Two pregnant does in the same cage will pull each others' fur, and may very likely try to use the same nest box, resulting in the loss of many of the babies as the does dig in the box and jump in and out. I don't believe one doe would deliberately kill the other's kits, but a stressed doe may kill her own kits, and many can be killed inadvertently as the does bounce and stomp around. One mama-to-be and one nest box, per cage, is the most peaceful arrangement.
Good luck!
