My conclusion is that for some reason he had to do a new mix (presumably guided by the old one). @steelydave might have more info?I'm curious about the mixing credits listed on the product page. "New stereo mix from the original analogue multitrack tapes by Michael J. Dutton" makes sense given that there was no dedicated stereo mix in 1976 and I believe it's been said here that the later stereo mix that made it to CD isn't very good (or am I confusing that with "Annie"?).
But what's up with "Additional quadraphonic remixing from the original analogue multitrack tapes by Michael J. Dutton"? I don't mean to suggest for a second that there's anything nefarious, I'm assuming something needed to be done for some reason and I'm wondering what and why.