Max current is the only thing that matter. "Voltage" of the motor is that the current you will get when you apply that voltage blindly - which doesn't matter when we are using drivers like polulu which limit the max current.
Your motor accept higher driving current, that's fine. (It will be a problem if the motor rated "voltage" is higher than your input voltage because that mean you could never get to the rated current)
Apply 12V, set polulu to 2.0A and you will be fine.
EasyDriver is fine too, but you can only get 0.75A - which is a bit far from the rated current of the motor - it might end up not working well besides an reduced output power, which affect torque/max speed.
Your motor accept higher driving current, that's fine. (It will be a problem if the motor rated "voltage" is higher than your input voltage because that mean you could never get to the rated current)
Apply 12V, set polulu to 2.0A and you will be fine.
EasyDriver is fine too, but you can only get 0.75A - which is a bit far from the rated current of the motor - it might end up not working well besides an reduced output power, which affect torque/max speed.