Q:

Dual casting different spells

I can't seem to find the information. Does getting the dual casting perk also work for dual casting different spells?
For example, if I have Frostbite in one hand, and Sparks in the other, will the combination creates something new, or will it just be better overall?
Thanks

A:

No. Dual Casting perks only apply to cases where you have the same spell equipped in both hands.
You can not combine spells to get interesting or useful 'combined effects'.

A:

The text of the dual-casting perk is:
"Dual casting a destruction spell overcharges the effects into an even more powerful version." (emphasis mine)
Since the hand animation changes when dual-casting the same spell and not different spells, and the perk description specifies singular, my guess is you cannot dual-cast different spells.
You can test this by using the impact perk, and seeing if you're still able to stagger opponents.
References:

http://www.uesp.net/wiki/Skyrim:Magic_Overview

http://elderscrolls.wikia.com/wiki/Perks

