I just got CatBus’ PM about this, and have downloaded the file posted by Puggo. Since I’ve been rather swamped with work lately I might not get to it right away, but I will investigate this mono version for any possible differences to the stereo mix.

Without having heard any of it yet, it seems likely to me that it would be a separate mix, but with only minimal differences in content. If the other two movies are anything to go by, there might be a few minor discrepancies in which sound effects are included, but probably nothing particularly significant.