Ben: There are a few minor dubbed bits that were missing in the TriStar master.
Very inconsequential of course but missing nonetheless.
Kain: We’ll stick to the Showa films, of which there are only four* films that have two dubs (
Ebirah thru DAM and
Hedorah). The international/export versions of the ‘60s trio were dubbed in Tokyo around the time of those films’ Japanese release, while GvH was dubbed in Hong Kong in ‘71 or thereabouts. After
Hedorah, Toho continued sending Godzilla movies to Hong Kong to be dubbed until 2004; none of the Showa films after
Hedorah were redubbed in America, although they were often heavily edited. (So consider
Megalon: Toho has an uncut international version, dubbed in Hong Kong. It's licensed by the American distributor, which uses the existing dubbed version. But to appease the MPAA and get a G rating, they have to cut quite a bit of content. So you have an "international version," which is unedited, and an "American version" of the same, which is cut to ribbons. Both have the same dubbed audio but aren't quite the same thing. If that makes sense...)
It sounds like you grew up with the most commonly seen versions of each film in the ‘80s and ‘90s. Except for GRA, which you didn’t see until later, you saw/heard American versions of the films from KOTM thru
Son of Godzilla (the international versions of
Ebirah and SOG weren’t available here until the Sony DVDs). You’ve said you’ve never heard the AIP American release of DAM, so that one’s easy.
Revenge was dubbed in America and there’s no export version (also easy).
You may have seen and heard both dubbed versions of
Hedorah. That was first released here by AIP as “Smog Monster,” which was twice released on video. If the title on the film itself was “Godzilla vs. the Smog Monster,” then the version you saw was AIP's. Later, in 1996,
Hedorah and DAM were picked up by Sci-Fi: these were the international versions of both.
As said already, the final four Showa Godzillas were only dubbed once each, all in Hong Kong. I know you don't care much for the English versions or anything about them, so I don’t want to inundate you with minor details: I’ll say that, judging from your comment, you saw the edited American theatrical versions of
Megalon and TOMG and the uncut international versions of
Gigan and MG.
If you’re curious as to how all that translates to this Criterion set: KOTM, KKvG, DAM, and GvMG are all exactly as you saw/heard them as a kid. The dubbed versions of
Astro-Monster,
Megalon, and TOMG are the same ones you heard then too, but aren’t the same edited versions you grew up with. (IOAM is a unique and somewhat complicated case but let’s just leave it at that.) Hopefully that’s helpful and informative.
*There is probably an international dub for KKvG but its release has never been confirmed, so for the sake of simplicity it’s not really worth mentioning here.