I have two breeds of ducks, I have 2 Khaki Campbells, and 1 Mallard, all hens. I have 1 Mallard Drake. I have someone who wants to buy Mallard eggs, It seems to be they all look the same? I will have to compare them all tomorrow when I collect eggs, but I guess th best way to make sure I get mallard eggs is to seperate her at night and let her out in the mornings after she lays her egg?