I have a D'Uccle that I think is confused too. Last year he was one of a pair that the hen went broody but I'd not saved her eggs so I got some "who knows what they are" eggs from a friend. Turned out she hatched a pair of mixed, a jap rooster, and a buff polish. The polish ran into a fence and broke it's neck but the other three survived. Well, the hen was killed by a predator when the chicks were about three weeks old, and the D'Uccle roo took right over. Acted exactly like a hen. He had helped her incubate them sharing the nest with her, and until one of those chicks was twice his size he went to sleep at night with his head...that's all that would fit...under the roo.
That roo, and the little Jap roo shared a pen peacefully. Neither one had a wife. I saw the D'Uccle do the dance, grab him by the neck and mount the jap rooster about two week ago. Usually the jap roo is the more aggressive of the two but both are very docile. The D'Uccle had him cornered and he put his head in the corner, squatted down, and the D'Uccle appeared to breed him although I do not think that is possible.
Fortunately I went to a show and bought the D'Uccle a wife...a very expensive wife...last Saturday. He wasted no time paying attention to her. He made her a nest and herds her into it, then blocks the doorway to it and urges her to lay. Since Saturday I've gotten two eggs from her. He is the best little daddy rooster and it was high time he had the chance to have a relationship that may result in chicks. I'm hoping.
Terry in TN