What exactly are you feeding them, including treats? And percent protein in their ration? What is the age of your feed? Do they free range? Size of coop? Run?
Most often, egg eating is a seasonal issue, occurring towards the end of the winter. If a hen lays a weak shelled egg, it's natural for them to "clean it up" as a self preservation thing. I've seen a definite correlation between shell strength and addition of multi vitamins. If certain other vitamins are lacking, she can't metabolize that calcium. Bored chickens can also become egg eaters. If all they do is hang around the coop all day, waiting for that next egg to roll out of the chute, that can be the highlight of their day, and result in egg eating. If they have reason to be out of the coop all day, they are less likely to be bored.