Am i talking a true golden duckwing, a different gold based pattern that used a dilute to resemble a golden duckwing, a silver based bird using mahogany or such to look golden??? Idk. I just know what breeds have a variety called golden duckwing by the APA.
I have raised a few golden pheonix and still have one rooster. They do seem to resemble a golden duckwing and breed true. Idk their exact genetics.
What I do know is a male silver/gold based leghorn and its color refered to as a golden and that it wont breed true. I once came across a variety of leghorn oversees that was called a golden duckwing and was to be a true golden duckwing. I never found much info of their true genetics (i believe they were really a partridge) but looked into the golden duckwing pattern. Found the same info you have plus a whole can of worms about the trueness of their being such a pattern and a lot of ideas on how it could be created.
I do know as far as having the true look and being able to breed true all I found was the pheonix and seen the others listed with the APA.
Thinking back maybe there was a golden duckwing american game too.