That mix is guaranteed sexable. Genetics can’t be altered. Solid male over barred female = solid pullets and barred cockerels.
That I understand, thank you. What I'm unsure of is if they actually sold me Dominant Coppers or if I accidentally got something else instead. I'm hoping I got what I paid for, because then I have two pullets and I really wanted the dark brown eggs. However, one looks more and more like a cockerel every day (much larger comb and wattles), which has me wondering about a mix up. At this point, not much I can do but wait for them to get a bit older and see how they turn out. If I did get something else, then at least I have an excuse to buy some Black Copper Marans chicks next spring.