Eating Eggs

Use a normal egg box. 

The reason they peck eggs is that they are situated in non viable locations.  An egg that can't be sat on is not liable so they will attempt to "clean it up".  There's absolutely nothing wrong with your hens they are acting perfectly normally it's your poor nestboxes which are inducing this behaviour.  Necking them as you put it won't solve this problem while ever you have nestboxes which don't do their job properly.  Either make sure they do or use normal boxes.

If your hens behave badly or develep bad habits the first place you should look for the culprit is in the mirror.  You need to understand what makes them do this and eliminate the motivation. 

The same applies to feather pecking and other bad habits they are usualy induced by misguided husbandry.

HF

if they are only eating the soft shelled eggs, broken eggs or those with thin shells then there is nothing to worry about, they are just getting rid of the evidence. Rollaway nest boxes are perfect so no need to change them. If the eggs are hard shells then you could try fitting a beak clip to the main culprit - this should hopefully stop them from pecking the shell. I wouldn't neck a bird for doing this unless the bird is aggressive to other birds as well.
You did right to ask as I'm sure you are not the only person to wonder about this and as you can see I think the birds are just doing what nature intended and removing any evidence (as well as getting some extra protein from the egg and calcium from the shell) 

I'm sorry if you were offended by my reply to your question.

I don't claim to be a world expert as you think and you are free to accept or reject any advice you get.  Chx will eat even normal eggs if they are in a non viable location as well as non viable soft and broken eggs and you did say your nest box was not doing it's job as it didn't prevent access to the egg.

My advice may have been a little blunt however if you can't accept advice given as a gift and are going to take exception to it and respond petulantly perhaps you shouldn't ask for it.
Best of luck with your eat eating problem.
HF

Thank you DD I don't think I was responding petulantly, the response from HF was couched in insulting terms and totally unnecessary ie 'look in the mirror'.  However, the matter is at an end.

I know this thread has been locked (thank you DD for doing this  ) but just in case Alisonwo or anybody else needs beak clips this is where I have bought mine from in the past:-

http://www.domesticfowltrust.co.uk/products/info_apb.html

Hope this helps