I just had a double yoke egg to hatch. It was on day 20. Only 1 of the yoke's developed into a chick., the other one quit really early in incubation. This chick is HUGE. It's bigger than my week old chicks. Is this normal when only one chick develops? It was in a batch of 20 mixed breed eggs that I put in the incubator, So I don't know what breed the chicken is, but it's egg was smaller than some of the other eggs. Let me repeat "this chick is huge"