Ok, first, I haven't done this and I keep my pens pure for pure breeds. I would like to put another coop in, but we'll see. But I have an honest question about how chicken fertilization works and how two roosters over a set of chickens could work. With rabbits, if you breed a doe of breed a to a buck of breed a and a buck of breed b, knowing genetics and colors, etc., you can easily pick out which kits are pure and which aren't. Do chickens not work this way? Theoretically, if you had two chicken breeds that were different enough (including egg color) in one pen with two different roosters, would you not be able to hatch out the chicks and tell at hatch based on down and other factors that the chick was pure or not? Did that question make sense?