I suppose it depends on the chickens, would they fight over the babies ect... My chicken was broody and after a week another hen went broody and kept robbing the eggs from the other hen, so I confined the hen to another pen and placed her on some eggs of her own... only for her to eat 2 eggs after a week of setting, and deciding to not sit for days, so in the end I am glad I segrigated her because im sure harm would have came to the eggs she tried to steal, or even worse the chicks that hatched could have been harmed or killed, she still now tries and takes over the chick that hatched and it is 4 weeks old now, so glad I have them in a brooder pen as im sure the hens would fight... its your call, maybe seperate and give them both eggs but in different parts of the coop or different pens...