It's true, most of the time a double yolker is much larger than a regular egg. But sometimes you can't tell, they just look like regular eggs. When birds are starting out laying all sorts of weird and wonderful shapes and sizes materialise. That's just the way it is. I'm sure if Tracy had known they were double yolkers then she wouldn't have set them but we are here now and all we can do is hope for the best and wish her well.