unless the subs have the same specs (power handling, frequency response. . .) you will need to make sure that if they are in the same boc that they are sealed in seperate compartments since they can move at different rates. will mess up the sound and could potentially damage the subs. they will most likely also need their own amp for each one in order to get them tuned correctly.
2013 F150 4x4 SCrew XLT 5.0L
Midwest Crew #22
Official FocusFest Event Planner