What I don’t understand about dual wielding

There are some weapons (like the starter weapon for the wanderer) don’t have two swords, rather they are two swords, and I realise that makes zero sense, but other swords, like the one that the grafted Scoin drops has two weapons when you two hand it, what’s the difference? What are these Double weapons referred as? Are they worth getting for a wanderer build? Also, I just started a dual wild bleed build and wandering if anyone has any tips or early op items