As a fan of both Patrick Sky and John Denver, I've also noticed this...

Patrick is one of the few who could match Tom Paxton's talent when it comes to satires. It surely sounds like a Patrick Sky composition. John Denver surely does have a sense of humor, but I also don't think he cold write something like this.

Problem is: Patrick's parody was first released on "Songs That Made America Famous" - 1973. John Denver's performance is two years earlier. So there is no possibility that John learnt it from Patrick's record.

Maybe John knew Patrick personally? I don't know, sounds plausible.