I have the 20th Anniv edition and disc 2 is labeled "The Jams". Is that the same thing as yours?
Not sure how it is labelled, but it contains live performances on the Johnny Cash show, some alternate takes, and some other songs that obviously didn't make the album. A very decent second disk of bonus tracks IMO and worth having, unlike many reissues with bogus bonus tracks that never get listened to a second time.