I'm a little confused.
Did you only have 2 eggs set?
And you have 2 brooding hens who are co-sitting on this nest?
If one is broken, it is gone. If the other isn't developing, you can let it stay with the hopes it will develop into a chick or that you may not be seeing the development that is there.
If you are certain that the eggs are bad, then pull them.
Hens may sit for as long as 5 weeks, so with the right breed, you can set more eggs and have them hatch those. That is hard on a hen, but some will sit until they hatch something. For those, it is best to reset and supply nutrition (if you ever want to use them as a brooding hen again).
If you aren't particularly eager to have these hens hatch anything right now, then pull apart the nest and block it. In a few days, hopefully they will have given up the idea.
As to a brooding hen, she will begin to lay after she has finished brooding, often after a molt. This can take anywhere from a month to several months.
LofMc