This sometimes happens when you have a bunch of pullets and young roos hanging out in the coop during the day. I am going through the same thing while my 1 1/2 yr olds are laying eggs, the 3-5 month olds are running around being nosey looking in the nest boxes, pecking, and when they break an egg find out it's pretty good to eat. I am in and out of there all day long, and they still manage to get 1 or 2 a day. Hopefully they won't make this a habit, and I think a couple of mine did this last year, so when they are laying themselves soon, they will quit doing this. However, it can catch on and become contagious, so just make sure you feed a good 16-20 % protein feed (not just scratch) and give them crushed oyster shell or cruched eggshells on the side for calcium. Layer feed does the same, but I don't use it if I Ihave chicks still running around.