Guy
Inkling
Those times it's been done it's usually a short sword combined with a long sword. Some southeast Asian martial arts use twin short swords. You could maybe research that some. Brian Boru's son supposedly used twin swords at the battle of Clontarf. Generally, though, twin longswords just aren't terribly practical. Short swords are maneuverable enough for it to work. The longsword/short sword combo makes sense because if the enemy gets past the longsword the short sword is there waiting for him.
Of course, in writing fantasy, you get a certain amount of poetic license. You don't have to be 100% historically accurate.
Of course, in writing fantasy, you get a certain amount of poetic license. You don't have to be 100% historically accurate.