I suspect you are dealing with the a second mutation of Rose comb(R2), research have found that it does not impare sperm motility as the regular Rose comb mutation,Then you can read posts by experienced breeders of Wyandotte like Foley who don't believe it's true or of little significance. I tend to follow what decades long breeders do and would not want dormant single comb genes in my Wyandotte. And have not had a problem with fertility though admittingly have only been breeding them for three years.
If a fertility problem arose would blame the individual bird and not it's two rose gene comb. I've had fertility issue with a single comb breed and once changing out the cock the problem was solved. I'd say the proof is in the pudding. As I have rose comb Wyandotte that do not carry dormant single comb, or it would have shown up in three years, the two rose gene fertility issue is proving to me to be overstated.