Here's a screenshot comparing both 4K BD mono tracks in Audacity.
"mixdown" is from the 2014 US MWNN Trilogy BD.
"original" is from the 2014 US "standalone" GBU BD.
It's clear from the waveforms they're not identical. I listened to them simultaneously ("mixdown" in left channel and "original" in right channel) and they go in and out of sync with each other throughout the film. It's clear that Chace Audio tweaked the track on the standalone BD. Now the audio credit is justified, unlike on the UK 4K BD and US MWNN Trilogy BD where it was utterly mystifying.
