Miyamoto Musashi was a major proponent of using both swords simultaneously. He won a lot of swordfights, but I don't know if that's what you mean by "combat."

Source: Book of the Five Rings, as well as the Ni-Ten Ichi Ryu school.

Fiore discussed ways to fight with two clubs, or staff and dagger. Fiore trained the leaders of a number of captains of Free Companies in Italy who may have trained their own men in the methods. So you might have see it on the battlefield in the 15th Century.

A number of manuals talk about fighting with two swords or two rapiers in the 16th and 17th centuries. So you may have seen them on a battlefield somewhere, but more likely in a duel.