Two weapons use

[fable]

What's the advantage of using two blasters (let's say) in a single turn when you can equip a single larger weapon that has double the possible damage?

[Ned Flanders]

I don't see any advantage other than you might be spending additional weapon feats where you don't need to. I usually cater to the default weapon foci an NPC has. For instance, with Carth, I stick with dual blasters because he's already got weapon specializtion with blasters. No need spending feats on heavy weapons use just because I've a found a heavy weapon capable of doing the damage of both blasters combined.

[fable]

I was thinking more along the lines of a laser rifle vs two blasters.

[Necrotaur]

The Pistol group has the Mandalorian heavy blaster or somesuch that is leagues above most other ranged weapons. I'm not aware of a rifle equivalent to it.