Glad you posted this as I have one egg at day 15 that I was sure had two embyoes at day 10. Mine weren't on one end and the other but more like one side of the egg had an embryo and I could see what I thought was another on the other side. The movement in this particular egg of much greater than in the other 18 I have in there, but I'm now thinking it is just a very active chick. I'm new to hatching so I wasn't sure what I was seeing, just knew that it appeared different than the others. I'm attaching an enhanced pic from day 9 candling.