Bro. I understand genetics. It's not possible for females to have single combs and males to have the appearance of no comb (or mohawk style comb), wattles, or earlobes, it's just not. Small combs and wattles are not the same thing. This is not like naturally polled livestock.
Unless you want to breed two completely different genetic lines:
One with single combs, and take only females to shows.
One with completely different comb/wattle genetics, so the males look like dubbed males, and from that line only the males are taken to shows.
That seems like a lot of bother to me, but might be possible if someone was determined enough (many years, many chickens involved in the breeding project, quite a lot of effort on the part of the person).
I agree that it would be genetically impossible to get both types in one single true-breeding group. Either you have the genes for the female single comb type (and the males have single combs too), or you have the genes for the males with fake-dubbed combs (and the females have a smaller version of that same comb type.)
It is not impossible if breeders took their time to make it possible, but unfortunately they wish to not. To say it is impossible would be to say that no chicken could have a small comb and small wattles, which do indeed exist. If it was impossible then my Easter Eggers would not have such flat combs that they look like they had been dubbed.
I wonder if you could breed them to look enough like dubbed ones that you could just enter the males in shows, not say anything, and not have them disqualified? That would be the real test of whether it looks "the same," to see if it even gets noticed by people who are used to looking at dubbed males.
In general, chickens for shows have to LOOK right, and people don't care too much what ancestors were involved to get that result. So if the chicken LOOKS right, they will probably not care if it was actually dubbed or naturally grew that way.