Not sure. I know theatrically, SW and ESB were both shown dubbed for some showings and subbed for others. ROTJ, interestingly, had no theatrical dub, so it was subbed-only (so another reason people may prefer the home video dubs is for consistent voice acting throughout the trilogy).

Given that, I'd assume the Japanese audience has always had a choice of subs & dubs on home video, since apparently they went through some trouble to make sure subtitled options existed theatrically. On VHS, they'd be two separate releases, of course.

But that's pretty much just guesswork based on what I know about the dubs. I could be wrong.

EDIT: Actually, our latest & best capture of the '77 stereo audio comes from a Japanese laserdisc, so there were definitely some options for hearing it in English (actually better than the options available to English-speaking audiences, it turned out...)