No, only the Waterfall, but I've a handful of GMVS DVDs and have just tested them - all R0. I've looked at rear sleeve scans of other GMVS releases online and no sign of region coding there either.
Both were short-lived "public domain" companies with only a couple of dozen releases apiece. They're
definitely connected, though I'm unsure exactly how. Nerdy I know, but I've been tracking outfits like this forever. In the case of these two, their releases are often credited interchangeably, regardless of whose logo they carry.
Like here.
At best, one is a repackage of the other.
I don't suppose it's possible to track down who added the GMVS?Either way, it isn't a huge deal: this is hardly a classic of the genre and I reckon all but one or two of its releases are listed anyway, so not much scope for confusion!