Torps are on shared cool down. No point running two at fore because you can only effectively use one.
Torpedoes are on a shared cooldown, it's 1.5s. 2 or Even 3 Photon Torpedoes can fire forward with no worries about the cooldown.
More Practically you can use 2 and some Torpedo DOFFs to get a near constant stream of the things. In STFs against the unshielded targets you'll be doing massive damage. Swapping back to an extra DHC will help on things that have shields.
If your going the twin Torps route I recomend using Photons. If I recall Cygones Maths correctly you got around 140 Torpedoes fired over 300s