There appear to be two slightly different retail versions of the game released in the US just over a week apart. Both are documented on Redump (http://redump.org/disc/12130/ from 4th November 1998 and http://redump.org/disc/31980/ from 13th November) and available on Internet Archive.
The differences are minor: the volume label is "BLOOD2RC5" in the earlier version vs "BLOOD2" in the later one. As far as contents go, the differences are contained to the help file (updated key mapping description, weapon and item info in the later version that suggests subtle gameplay tweaks might be present as well?), the Naga model, the end credits (the later version removes the final part where Monolith disses various things) and SOUND.REZ (although the actual contents inside appear to be identical).
Although this perhaps isn't all that relevant to this wiki, I think it's an interesting detail to note.