I know of three. they are all mentioned somewhat on the imdb page. we now have a nice DVD set of the US and Japanese versions, but I have also seen a 76 minute "International" version from a Greek copy called "Katango's War" in the subtitle.
in this one, with the standard International dubbing, we get to hear the monsters referred to as "Frankensteins" and by their given names of Sanda and Gaira.
it's interesting to say the least. the quality of the original VHS tape I saw many years ago was not great, given the PAL to NTSC transfer and however many generations down it was by the time I got it.
this is a movie I really enjoy still, after seeing it as a kid. had no idea what it would be like and it never failed to entertain me. it's also one of the movies where the Japanese military actually had some success in fighting Gaira. they would have done him in had Sanda not come to his aid.
much to Sanda's chagrin later on!