I don't know. Some people very successfully have broodies together, either sharing the mothering duties or raising their own broods. Others have problems. I can tell you a few things that might happen. I cannot tell you what will happen in your specific circumstances.
1. They might get along great with absolutely no problem.
2. They might fight over eggs or chicks with eggs or chicks getting hurt or damaged in the process.
3. If they are to hatch at separate times, one broody might steal the eggs from the other. Yes, they can carry eggs from one nest to the other. If you do set eggs with different due dates, you need to clearly mark which egg goes under which hen and check them to straighten out any mix-up.
4. When one hatches, whether they are setting on separate nests or even on the same nest, one might kill the other's chicks since she sees them as a threat to her own, even if hers have not hatched yet.
5. If they are on separate nests with separate due dates, when one hears the other's chicks hatching, she may abandon her nest and go to the hatching chicks. Once there, they broodies may fight or they may work together to finish hatching and raise the chicks.
Again, I cannot tell you what will happen with yours. Many people have multiple broodies and have absolutely no problem, yet all the other things I mentioned have happened. Good luck, whatever you decide.
