msycamore said:

This info really confuses me, I always thought the 35mm Dolby mix was done first but the 70mm prints with the six-track was sent out and heard by the public first. Can someone please explain this?

I think there are many options:

Perhaps these guys don't really remember

Perhaps they have all a different version of the story, depending on their role in it, and "re-edit" the truth each one his way :)

Perhaps it is too complex to explain in an interview or they want to present the best story for anyone thinks they had so much pressure that they've done lot of mess

ect... ect...

Then I' be more inclined to believe the first version you quoted. The consideration I personnaly have for Ben Burtt (notably the importance he likes to show about his work as I see him) reenforce that point.