Hmmmm
Mayhaps you could plug in two mice and control each gun with one mouse
That would be an amazing gimmick to revolve an entire game around, if it was a rail-shooter..
Hell, you ever play one of those arcade shooters with the big plastic guns, set it for two players, and go akimbo? Sure you need twice as many quarters but it's fun as hell.
@KingJoker - I'm pretty sure they've specifically stated that Gunslinger can choose to use just one handgun and still be totally viable, so I don't think most of his inherent benefits will be specific to dual-wielding bonuses.
Most likely, some of the skill-choices from every 5th level will give you the choice between something Dual-Wielding focused and something more related to accuracy or crit damage or somesuch for the single-gun-users.
So yeah, you can choose to be a two-pistol hollywood movie badass OR you can play as the humble veteran police officer, or some random civilian whose never owned anything bigger than a handgun or some character like that.