The Anthology 1–3 audio series, you mean? Some tracks on Anthology 1 have been fully demixed-remixed back to mono, while other originally mono recordings have subtle stereo ambience added. They either did not go back to the multi-tracks for everything or decided to honour the original 90s set-up, since some 4-track recordings are still in mono, though still remastered. Other tracks which were in mono are now actually in stereo. Certain live recordings have been demixed-remixed in stereo, while other tracks are simply remastered from the same source. Many tracks have been very slightly extended or trimmed at the beginning or end. A couple of songs are edited differently from the 1990s series or the 2011 remasters.