Dual-wielding interaction with Hammer of the Gods

This might be a noob question, but I'm a bit confused. I'm planning to swap to my weapon set 2 for better Hammer damage on bosses, using dual-wielded weapons with +6 melee skill mods on both. When I equip two weapons, the Hammer DPS stats show two separate damage numbers: "main hand damage" and "off hand damage." Does this skill even use those weapons separately for hits? With a 24-second cooldown, how does that even work? Or does it only use the main hand for casting?

Uses both weapons.

I also see that HIT damage is shown only once, but there are two bleeding damages for each hand. Do these stack up, or should I add them and divide by two?