Mage + mage or mage + necro?

[Tallenn]

Starting a new duo with my wife soon, and am considering the two combinations above. At first, I was just going to go with 2 mages, but then considered that a second mage may not be all that helpful, since a lot of the damage comes from the fire pet's DS. Thus, the question.

Can a second mage add as much or more to a duo than a necro? If so, which pet should second mage use? fire or air?