I have the Region 2 Japan DVD and can confirm that the English track is in dual-mono.
Here are the audio specs from the back of the case (translated from Japanese):
1: Japanese (2.0ch stereo)
2: English (2.0ch monaural)
From having watched the English track, I could tell it had not been remixed. The music has the same muffled distortion as on the R1 Fox DVD.