You probably have eggs in all different stages of development. Since you have two hens, you might try this:
With a black sharpie in hand for marking, and two or three cartons handy for sorting, candle all the eggs, take out the ones you don't see any development in. Those are called "clears". They may be infertile, or they may be brand new and haven't started yet. Either way, take 'em out. Put clears in one carton. Then, put the ones with dark blobs that look about the same stage in another. Put eggs with veining and what looks like a dark spider in another. Or whatever stage of development you seem to have the most of. The older stage ones, mark with a guessed at date, or "O" for older, or whatever word or number or symbol works for you. Stick those under one hen. The others, the spider-and-veins-stage eggs, mark differently fron the first set, and stick them under the other hen.
If the first bunch hatches nearly at the same time, you might be able to save most of them. At least some of them. When the first ones hatch, if both these hens are together, they may both leave the nest with the chicks. You might be able to separate one hen with the chicks, and perhaps the other will continue to set on the other eggs. It would be better if you could separate these girls, though. Stick one in a coop or big dog crate or something with her share of the eggs, cross your fingers and hope for the best. Then you can let the other hen stay on the original nest. But check everyday, and remove any new eggs that get added.
Good luck with this! Let us know what happens, and I hope you didn't already kill the eggs by shaking them.