Ok, in the meanwhile, let's try to do some exercise:
first of all, a useful thread about JPN MVS labels:
http://www.neo-geo.com/forums/showthread.php?206106-Jap-MVS-Box-Labels-in-deep
Please note the *foreign* Fighter History Dynamite kit, with *Japanese* title on BOTH the sides of the ~square~ label.
Please note that such japanese -style label is above a first one, which clearly shows *Karnow's revenge* on the white side (following the usual rule).
My idea is, the label underneath is a Japanese one, and the above is , as often happened, a relabeling for export use (like ASOII/Alpha mIssion 2 AES carts).
Can't say why it kept the JPN title on both ides, even if the original label beneath says they already decided the title for foreign markets….maybe it has to do with the legal issues with Capcom, who knows.
Now, below the pictures of an "export" Power Spikes II kit (AFAIK the only kit available, please correct me):
Another official foreign release (all artworks are indeed in english), but with an uncommon japanese-style label.
Now, back to SuperVolley '94 kit, seems that the flyers are quite the same (not completely, far from Spanish language) and the box label differs, so it could be an early run, but for foreign market.
As seen many times, no pattern can be really read, but I think that SNK used square labels also for foreign markets (1994?), deviating from the usual rule square=JPN, horizontal label= US/EURO, and both games are probably foreign-only releases.
A wild guess: "SuperVolley '94" has been retired from JPN market due to legal issues, explaining why they had to quickly change the title (the code ROM) and keep only foreign versions.
Edit:
for reference, the flyer: