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The Crossbow Expert feat lets you use a Hand Crossbow in your offhand and take a shot when you attack with your main hand.
Most people I've seen, seem to think this will allow Dual Wielding Hand Crossbows. What I'm curious about is if you get dex mod to damage on the second shot. There are two lines of thought I've come up with on this.
Either it follows the TWF model, where you do not get the offhand weapon's modifier without an extra feat, or it follows the Monk's Bonus attack model, which grants the modifier.
I'm not sure which way to land on this.