I have stude Physic 3 years to know that is impossible.Ok, Mars getting closer i believe.
But be an Earth Moon its Impossible.
Firts we could have 4 moons (If it was possible) Moon,Mars,Phobos, and the other moon Mars have.
Second Mars magnetation will atract Moon , and Harm us from earth.
And then the Earth magnetation that would atract Mars (Earth is Bigger kids =D )
and at like an asteroid and killing us all =D
Moon no please!!!
(Ready for get thousands of bad responses to my comment and my english in 3... 2... 1...)