I've read that about Wayne taking care of people. Read one time that Bruce Cabot was basically broke later in life and The Duke would give him roles to help him out.
I'm a little behind...only have maybe 20 of his movies. Don't watch much. Really don't care much for pre-1950 movies of any kind (unless a classic good one). Guess it's just the difference in photography, sound, etc .... right about then the technology improved a lot.
But the double character in Katie Elder still puzzles me...especially if you're paying attention you can easily tell it's the same guy. You're right Karl Swenson.
Another one who was in it twice, but probably so in many of them was Wayne's double. Played one of the bad guys at the bridge shootout, and was the double for George Kennedy when The Duke hit him with a 2x4 in the funeral home lot. Probably did a few stunts for Wayne in the movie too...