But the 35mm stereo and 70mm surround mixes are no less "original." All three were heard in 1977, albeit in different theaters.
Of the three, the mono mix was completed last. So chances are the music you remember during the duel wasn't "edited out" but edited in after the 35mm & 70mm mixes were already finished.
Check out this page to hear clips from the mono mix, and see if that's the announcer's voice you remember.
No official home video release has included the mono mix, although bootleg versions do circulate. One forum member has a VHS tape from a television broadcast with the mono mix, which is being restored by an audio specialist (another forum member.)
General consensus is that the '93 laserdisc soundtrack most closely resembles the 70mm surround mix, with a few changes.
If you're hoping to hear the mono mix on the forthcoming DVD, don't hold your breath.