Topic. If I dual wield bound swords, and I have the conjuration perk for dual casting, does it make the swords last longer?

No. If you dual cast bound sword, you will get one sword in your main hand that gets the extended time. You would then have to separately summon a normal duration sword for your off-hand.

Yeah, dual casting for Bound Swords dual-wielders hurts more then helps.

How so? I am loving duel wielding bound swords.