I was once in a folk festival workshop with Dave and Utah so yes, they have swapped songs on at least that occasion and, I would guess, many more. They were certainly friends, maybe not close friends, but they knew each other and there seemed to be genuine affection between them.

As for political organizing, I doubt it. Dave was a Trotskyite and Utah was an IWW anarchist ("an anarchist is anyone who doesn't need a 'cop' to tell them what to do").