I bought the ...SAD SONGS IS ALL I KNOW version on vinyl when I was in high school, sometime around 1984 or 1985. I recently found an old essay or some writing for high school where I mentioned I had bought it.
There was a recent release of the San Diego 1969 show that claimed to be from a KSAN broadcast. It turned out to be just the audience tape that has existed for years. I think this is probably a similar situation, and it is more than likely just the well-known audience recording. I would love to be wrong, of course, but I've seen too many bootlegs that made similar false claims (soundboard, radio broadcast, etc) to believe it.