Rogues have two daggers.
It's not clear and you're not able to equip 2 separate daggers to gain extra stats or whatnot, but with no shield you attack twice per action - and see two daggers hit.
But it would be nice if this was made clearer on the items and on damage shown on your character sheet.
Really? Do you only see the second dagger in combat then? Because I just started a new game with a rogue and shadowblade and none of them had two dagger that I could see.