@Chukkensorc and @Cassiano, the property you're looking for is "Ammunition," of which the Hand Crossbow has (in addition to being "loading" and "light")
Each time you Attack with the weapon, you expend one piece of Ammunition. Drawing the Ammunition from [a quiver, etc] is part of the Attack (you need a free hand to load a one-handed weapon) [...]
Given that in 5e (not BG3) rules you only have 1 free item-interaction per turn, you can't actually dual wield Hand Crossbows. Picture an optimal starting situation, where both are pre-loaded
- Turn 1: You fire both crossbows with your action and BA. Then you stow one crossbow so that next turn you have a free hand to load with as part of the attack.
- Turn 2: You attack (loading and firing) with your equipped crossbow, then use your item interaction to draw the other one. However, it's not loaded and you don't have a free hand to load it, so you can't fire it with your BA.
You can, using the alternate turn stowing-and-drawing of your melee weapon, dual wield a hand crossbow and a melee weapon. The downside is that every other turn you wouldn't be able to make opportunity attacks because your melee weapon would be stored.
Of course, in BG3 you can freely equip and de-equip items, so dual wielding hand crossbows would theoretically work.
