You would think it's that easy, but it isn't. Not sure if you have the moonroof, but in mine, the lights seem to rely on each other. I took some apart (right down to the circuit boards) and had a look. Unfortunately, while they plug in, they didn't work... One would come on while the other would turn off... it was very strange.
There are a few variations of the dome lights in this car, though, so maybe you would have better luck. It might be easier to install 2 of the passenger-side moonroof model overhead lights, as there is only one button to allow it to be turned on, but otherwise controlled by the main light unit.