I'm thinking of putting together a cnc plasma table. I'm on the fence about using one per side of x axis with rack and pinion or tie both side together with chains and sprockets using one motor. I prefer the two motor method because I think it's cheaper but not sure how to sync the motors together. Does Mach3 software automatically do that or is there any special configuration?

Yes you set up the motors as master and slave in Mach. It works extremely well as long as both motors and drive trains are the same.
Hood