Not that I am that picky over who lays what. Cause I try to keep similar bloodlined birds together in the same pen/coop. But, OCCASIONALLY I see one of my hens on a nest. I go back to see the egg. Each bird has, in some cases, definite identifiable characteristics that can be seen with her eggs. Maybe color, or shape. I have a Black Orp who's eggs are bigger and have a different shape egg then my other two in that pen/coop. I know her eggs. And really don't care. But, I know when it is her egg. Alot of the Show breeders, will simply put out their best hens into a small breeder pen, then after the deed is done. They have that bird to itself for several weeks for eggs collection from her. That way they assure that their getting their best Roo on their best Pullet. I am not that far yet. I keep all my Blacks eggs, and hatch every single one out. But someday........