Hi I currently have 4 duck eggs incubating at day 21. I have been candling and they're all moving about happily. What I've just noticed is that one has an aircell at both ends and another has the duckling developing on one side of the egg only. I don't know how long they've been like this because as soon as I detect movement during candling I return them to the incubator. The other 2 eggs look perfectly normal. Weird!!