A friend mentioned that he had a Blue Note stereo copy, which sent me to Google to do some research. "A Night at Birdland" was recorded in Feb. 1954, way before Blue Note was doing stereo recordings. Rudy van Gelder (chief engineer) didn't even own a two track deck until 1957... so some the early stereo releases from the late 50's and early 60's that were re-releases of popular mono recordings were based off of the one track master tapes. They were some sort of signal manipulation. So if looking at early Blue Notes, be aware that stereo releases of performances before '57 may not be what you think they are.