Rofl. Not Kun's double lightsaber, which he wielded like a single blade, and which died with him until the rise of the New Sith Order.
What the..... Bandon used a bloody double saber as did Bastila, and Revan did great against them. And if he did use it like a single then he's basically just using the single handed Forms, in which Bane is well versed. And If he did use it in an odd way then it could be equally argued that Banes 'curved hilt' could throw Kun off in a simular manner.
Because he possessed a double blade with a hilt that was the size of a single blade, allowing him to wield the blade as one would wield a single blade, or a double blade.
So? Bane can beat both.