I play with another bassist in our litigation in-house band. It works well and is fun. Burkhard, a finger player, plays mostly Fender 5-strings with a crisp sound, he lays foundation unless he's slapping, and I, a pick player, play short scale Gibsons with a fuzzy sound, laying foundation when he's slapping and "lead baritone" (lots of high register, bending and chording) when he is laying foundation. We never need to have the basses run over the PA, with two bass rigs left and right, we're the stereo bass attack!
I'm surprised that hardly a professional band ever uses two bassists, the "overlapping frequencies" argument against it is vastly overrated in my opinion. It all comes down to the two bassists having discernibly individual sounds (and rest assured: nothing you play on, say, a short scale Gibson Flying V bass sounds as if it was played on an active Fender 5-string Jazz) and styles (Burkhard's and my playing are in parallel universes that hardly ever cross unless we want to). If Geezer Butler and Chris Squire plyed in the same band, I believe that would be just as complementary as Sting and Larry Graham. I believe I'd like to hear Glenn Hughes (for his rhythmic accents) and Paul McCartney (for his sense of melody and harmony) together, I could envisage it just sounding fine.
