First I had to find out that the highlight of one of my favorite Duke Ellington records was at least partly a studio confection. But I could deal with that — after all, the epic Paul Gonsalves solo on “Diminuendo and Crescendo in Blue” was the real thing, even though the rest of the concert had to be re-recorded in the studio to bring the sound up to par. But now it turns out that one of the spookiest moments in pop music was actually the result of the tape-slicer’s art. The record in question is still a great one, but jeez . . . what other surprises do these archival recordings have in store? Are we going to learn that nobody yelled “Judas!” at Bob Dyan during that famous concert?