Before I set a clutch I cull out the unusually large eggs and the unusually small eggs. Huge eggs never hatch and small eggs produce small chicks that have a failure to compete with the rest of the hatchmates.
Candle the egg and you will likely be able to tell if it is or is not actually double yolked. If it is, it is not advisable - arguably irresponsible - to set it. Even if the egg is not double yolked, it's size and shape would dissuade me from setting the egg. You really want to pick those eggs with the "perfect" egg shape and size for setting.
Did you buy them? Not very good if you did, there is a thread on here somewhere about someone who tried to hatch one but but chances are tiny if not nil you would succeed, most attempts end in tears and dead in shell chicks. if you bought these you should have been given eggs with a better chance of hatching.
Also a good point - someone distributing eggs for hatching ought to be familiar with the selection of eggs for hatching and distributing responsibly.
I hatch lots of eggs,I always try to hatch all my double yolkers. So far no luck. I actually have one in the incubator now. I'm doing a dry hatch this year. Will see if this makes any difference.
