Normally they don't, but I'm wondering if maybe your chicken's shells are a bit weak. Maybe you could add some crushed oyster shell, in a bowl, into the coop so they can eat some of that. It'll help the egg shells to be stronger.
We have a feeder with egg shells in their house along with a water can and another feeder of laying feed. This started a few weeks ago and then it got better but 2 days this week 4 eggs were broken and those days I only gathered 1 egg each day. On Wednesday all the eggs were broken.
The house is 8x10 with a lot for roaming. we have 6 laying boxes there are 13 Rhode Island Red hens.
Once chickens start to break eggs or find eggs with weak egg shells, it becomes a hard habit to break them of. Egg eaters are hard to cure. I had this happen in my flock as I have an older hen that has a hard time putting a good shell on an egg anymore. So she was leaving yolks and membrane only eggs all around. My flock went crazy checking every egg, breaking into eggs, throwing fake eggs out of the boxes in hopes to break them open.
I was able to help her put hard shells on with some added human grade calcium pills on a daily basis. But to stop the egg eating, I found that curtains hung over the nest boxes stopped the egg eating. The chicken slips through the curtain, in the dark she lays the egg and doesn't mess with her eggs or anybody elses eggs in the dark.
I have since thickened this layer and have solid curtains over these to keep the boxes really darkened. (there is 2 boxes here) You can peel up the center for them to get used to going into the boxes at first. But once they know how to get into your boxes, you can leave the center down like I have here. Now the hens don't go cruising for eggs from the outside, they go in and do their business and then leave things alone. Always keep a fake egg in your nest boxes. This helps to teach them that eggs are impenetrable. And always collect your eggs as much as you can at first so that eventually the break this habit of egg eating. I have never had another episode since using curtains.
Make sure the egg shells or oyster shell is always in their faces. Chickens will not go looking for it. So keep it right next to the water and feed they are always using. Keep the treats down to a dull roar so they are mainly eating their calcium enriched layer feed. Good luck!
All excellent ideas from Two Crows! I did think I had an egg eater this summer. There was this hen who kept laying her egg outside in the chicken run. It would get pecked and broken and the whole flock would be around that egg, waiting to pounce! And then I noticed some fully eaten eggs in the nesting boxes (only the shell remained). I started letting them free range more, and this habit stopped.