Coupling servo-motors
Your difficulty will not be lining up the motors initially, or dialling in the opposite drive operation, it will be maintaining that alignment when faced by the mechanical and electrical position drift of the servos over time.

Servos don't have a torque output, they have a position output, though their torque when trying to get to that new position is limited. This means if the positions are mismatched beyond their deadzone, they will keep on driving, fighting each other, using power and getting hot. You would be creating the very situation you are trying to avoid.

If you have room for two small servoes, then you have room for one larger servo. Use a bigger one with adequate specification.