Does dual wielding wands give bonus spell damage?

Disclaimer: I am new and am trying to learn more about the game.

Does dual wielding wands give bonus spell damage if both wands have a bonus to spell damage modifier? For example, if I have two wands that say 21% increased spell damage, does this stack? Or does it mean I would only get 21% increased spell damage for the spell socketed in the wand? Meaning if I have Arc socketed in one wand, I wouldn't get 42% but only the 21%?

They stack and are global. That means...

You take all your sources of increased spell damage and add them, so 21% on two different wands would give you 42%.

That increase applies to all spells that you cast - not just things socketed in that wand.

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GreyLensman wrote:

They stack and are global. That means...

You take all your sources of increased spell damage and add them, so 21% on two different wands would give you 42%.

That increase applies to all spells that you cast - not just things socketed in that wand.

So then it's better to dual wield wands vs going wand and shield if you want damage output?