I have never had a roo with one waddle in any breed.
It could be that someone is passing around poor quality stock then. I got rid of him when I saw that one of the cockerels that he was the daddy to had the same thing. It was a trait that I wont be passing on in my lines. So all of his sons were culled and the girls are used just for eating eggs now. I don't want to pass on a bad trait.