Yes, you can combine the shots from both pistols (effectively giving you one attack roll and one damage roll). Doing so gives you either +2 on the attack roll, or +2 on the damage roll.
Narrative-wise, you place / time your shots to give you a benefit - either both shots hitting the same spot to try and increase damage, or fire a "spread" of shots to better the odds of you hitting a target. Numerically, it would only really be beneficial for tough opponents.