What you're referring to is a Production credit, not an Engineering credit.
Paul Rothchild produced the Doors first five albums, but Bruce Botnick was the Recording and Mixing Engineer on all 6 albums, alongside being a Co-Producer on "L.A. Woman" (hence the production credit on "Love Her Madly" and "Riders on the Storm").
AFAIK, Botnick was the only Quad mixing engineer for this release.
I thought that might be the case..but I was holding out hope...oh well...just happy to have any Doors material...