I have a blue hen that laid two batches so far. Each time I saw a long egg in her nest. The first time was in Sprng so she laid a lot of eggs and a few eggs did not hatch including the double yolk . The second batch was in summer just a couple months ago. Fewer eggs and hatched all including 1 double yolk. I like this hen due to the fact that she lays a lot, good setter and ,,,, always double yolks.  Welcome to the site and I hope you like the hen with double yolk too, whether for hatching or for breakfast. Smile !