I have a duel magic wielding mage.

And I was wondering. Does combining magic give effects?

Like on Dungeons And Dragons Online and Dungeons And Dragons any, I presume.
On DnDO you can duel wield a fire weapon and a ice weapon and create Steam.
Steam hurts everything and damages a lot. A enemy can be immune to fire and ice, but nothing is immune to steam.

So is it like that on skyrim?

You duel wield fire and ice magic or weapons you get steam? Or other combined effects?

Anyone know?

not that I'm aware. but it should increase the power of the spell

You don't get combine effects like that. But you get one effect then the other one. So, you could imagine to be like Steam. Only the visuals will not be the same.

In a word, no.

It is a neat idea though. But not everything has a nice middle ground like fire and frost create steam. Like, what would the middle ground be for sparks (electricity) and fire?

It is a cool idea though.

I swear I remember hearing Todd Howard in one of the pre-release interviews saying that this was an idea they were toying with since they were cutting spell creation, and it would allow some limited ability to "create" spells though combining different effects through dual casting. Maybe I misunderstood what he was saying because you sure cannot combine effects through dual casting in Skyrim. It would be cool though. Some spells wouldn't combine well and maybe those would just blow up in your face, but wouldn't it be great to combine a stoneflesh and a flames cloak to get double strenght in both? If you had perks in dual casting for both schools it would make sense that you could do something like this.