Also I forgot to mention that there is a d'Uccle thread and the breeders hang out on there sometimes. You might try reading some of the recent posts on that thread to garner more information.
https://www.backyardchickens.com/t/269521/duccle-thread
I used to have some golden necked d'Uccles. I only had a few.
They are friendly, wonderful chickens. They are hawk bait, and aren't very cold hardy. Additionally, the hens are so very small that I wouldn't recommend having them in with large fowl roosters.
I noticed two "styles" of my GNs...