What books are those? Can you share title & author?My 4 GLW all have a single comb. My books say that is correct what they have.
I have always heard and read that Wyandottes are supposed to have a rose comb. They do sometimes produce chicks with single combs, but those chicks are not considered correct for the breed (rather like one with way too much black or way too little black would also be incorrect.)
Since what you found is different than what I've always found, I'm definitely curious to learn more.