Good question and the answer is, of course, it depends.
Hans is, so far, the sole distributor of Stendker discus in the US. So all his fish come from the same 2 - 3 Stendker hatcheries. Kenny works exclusively with Forrest, who has his own discus strains, but also has fish from other farms. Kenny's fish is exclusively Malaysian.
While other sellers sell discus from breeders, I'm not aware of anyone else who has an exclusive relationship. That is to say, not all their discus comes from a single farm or even a single country. Discus can come from China, Taiwan, Vietnam, Philippines etc. Malaysian discus tend to be pricier, but usually represent the latest varieties.
Hope that helps, Willie