John Wayne appeared with Duke in a series of B movie westerns in 1932-33 and both seemed to get equal billing(six I believe) . Most of them were remakes of old Ken Maynard pictures from the Twenties. I’ve been watching some of the old B movies Wayne made before his big break in STAGECOACH in 1939. From what I’ve found, they even used a lot of stock footage from the Maynard westerns, usually distance shots of a man, supposedly Wayne’s character, on a fast moving horse and a few others where you couldn’t see faces.
Duke certainly was a wonder. In RIDE HIM, COWBOY, Wayne proves Duke was not a killer by riding him and the horse seemed to take to him immediately. After trying to buck him of course. He established himself as Wayne’s ride by, in one scene, unsaddling Wayne’s black horse with just his teeth and running the mount off. In these four movies, he did all sorts of tricks, usually involving pulling up trees or posts he’s tied to to race to the rescue. Wayne was a different character in each movie, always John with new surnames, but the Wonder Horse was forever Duke.
One thing I found odd in my research. Wayne was not particularly fond of horses. To him, they were just tools of the trade in making cowboy pictures.