I can understand why you might want to use more than one, to have a fore and an aft torpedo, or two in the front, etc.
But honestly, it really doesn't need to be. It's already a 180 degree torpedo. To me, you really only need one:
If you run beam arrays or DBB, you only need one to help better cover your sides a bit, while still firing torpedoes regardless. It can be good to put it in the back actually, so you have a more often-firing aft torpedo, and use something with a little more punch up front, such as a normal quantum.
If using a single cannon/turret build, you might want one in the front, so you can almost always be firing all your weapons as long as you are roughly pointed at the enemy.
Anything else...you're better off with a slower recharging torpedo in the back (like a tricobalt), or using a mine.