The weapons selected for quick draw can be used as paired weapons, meaning the character can draw and shoot or throw two simultaneously at the same target, inflicting full damage from both weapons, but counts as one melee attack. Not applicable to magic spell attacks or the bow and arrow.
In the alternative, the two-weapon attack can be divided between two different targets visible to the Battle Magus and within his range of peripheral vision. The divided attack counts as one simultaneous melee action against two different foes. The quick-draw initiative bonus still applies, but the shooter must roll two separate times to hit each target (roll to strike for each) and the bonuses to strike each are reduced by half.
Note: Parrying is not possible when two items are being used as paired weapons, but the character can dodge (which uses up one of his attacks) and counter.