I recall a thread on this topic floating around not two days ago. I'll try and find it, but in the meantime, here's a search on the topic
From the posts in the recent thread, it appears that some people have had success, others abject failure. If you have limited experience with broodies, I'd suggest collecting and marking the eggs your want to hatch, and waiting until you are convinced that either hen is 100% committed to being broody (only leaving the nest once a day to eat, drink and poop) and put the eggs under her (this ensures that they will hatch at roughly the same time, and marking the eggs lets you collect any additional eggs that may be laid).
At the same time, break the broodiness of the other. Lots of threads and approaches to breaking broodiness, but putting the broody hen in a small wire cage (with food and water), suspended off the ground for 3-4 days usually does the trick. Again, search for threads on the topic if thats the way you wish to go.
All the best with whatever you decide.