__________________ RealistRacism: "Sheevites, much like the Banites, were meant to increase in power with each member. From Lightsnake to Gideon to Azronger, this was supposed to be the case. However, knowledge must've been lost in some kind of Gravid-like incident, as Az turned out to be a mid-tier debater with a sub-par track record, sh!itting all over Tempest's legacy. Sad."
It should be harder to defend against an opponent wielding two separate lightsabers. Two separate lightsabers can attack simultaneously from completely different vectors. Meanwhile, a double-bladed lightsaber actually reduces attack options (For example, a perfectly vertical overhead strike wouldn't work with a double-bladed lightsaber, you would impale yourself), and as long as you know where one blade is, you know the other blade is facing in the exact opposite direction.
There's no question in my mind that a duel-wielding opponent should realistically be more deadly than an opponent with a double-sided lightsaber.