i always divide the babies because the moms tend to either scuffle over the babies which results in scrapes and scratches on the delicate pinks or one mom basically dominates the other and takes and keeps most of the babies. if the litters weren't too big the pinks that are being nursed by the dominating mom are usually okay, but if both moms had 15 babies that's just way too many for one mom and the pinks tend to suffer--the stronger ones get all the milk and the weaker ones get none.

once i tried to keep two moms together that didn't have too big of litters because they didn't seem to be scuffling, but the mom that only got 2 or 3 babies of her own seemed to get really depressed. seriously--she got poryphorin all around her eyes and just laid there on her pups so sad-like. i removed her and gave her equal pups and she perked right up, the poryphorin went away and everything was fine.