The version I have is part of the "Miles Davis and Gill Evans Complete Columbia Studio Recordings". In the book that came with it they explain the stereo vs non-stereo issues around "Miles Ahead". The original sessions were done in May of '57 done on two track (best I can decipher from the writing, which is not super clear). During those sessions, Miles skipped several solos during 4 songs, "Springsville", "Miles Ahead", "New Rhumba" and "I Don't Wanna Be Kissed". Miles returned to the studio on August 22nd to do those solos. They had a three track for that session. Unfortunately, instead of having the earlier master on two tracks and Miles' overdub on the third track, they had the edited earlier takes in mono on one track, Miles overdub on the second and a combined mono mix created in realtime on the third track. To complicate things, apparently the mono recording that Miles was playing to in the overdub session did not play at precisely the same speed as the stereo two track, causing it to be out of sync with the stereo track. This mandated that these 4 songs had to be in mono, at least at that time.
The original issue was in mono.
A re-issue was done in 1987 in stereo. The technology wasn't good enough to overcome many of the obstacles and this issue wasn't very well though of. The 4 songs had to be "creatively" edited to make them stereo. This included different edits from the original issue using different takes made during the various recording sessions. Sometimes the overdubs were removed, other times they were creatively added. The non-overdubbed songs also had some different edits. These "altered" songs were not received well so Columbia pulled it and re-issued a mono version which was virtually the same as the original. A psuedo-stereo version is also mentioned but they don't give details other tha it was in '93.
As digital technology advanced, the sync problem between the overdubs and the original two track stereo could be solved. This lead to a true stereo version that held true to the original. I believe that this version was the '97 version.
The "Miles Davis and Gill Evans Complete Columbia Studio Recordings" is an excellent recording for Miles fans. It has "Miles Ahead" "Porgy And Bess" "Scetches of Spain" and "Quiet Nights". In addition it has tons of alternate takes, overdubs, and rehearsal sessions. For example, "Miles Ahead" spans almost two and a half CDs with all the different takes. In the booklet, it even has a breakdown of how the songs were edited and which takes were used where to create the songs. The CDs even use indexing to signal when edits take place in the songs. It's a really nice collection.
That's odd, since all vinyl editions and earlier CD editions of that album had been in either mono or 'fake stereo' (also called 'pseudo-stereo'). 
