We've had one chicken sitting on a few eggs for two weeks. This morning another hen was sitting on the nest. Is it normal for them to give each other a break like that?
No. What you are probably seeing is hen #1 hopped off the nest to go grab a bite and hen #2 saw an inviting place to lay today's egg. Hen's prefer to lay where there are already eggs. Mark the hatching eggs so you can remove the fresh eggs everyday.