In my ford handbook folder I have a key code card. It does have a four digit number written down. I have a touchscreen satnav cd/rad and I also have the DVD player for the rear seats, and the manual for that implies it needs a keycode if the battery is disconnected/replaced. In the old days, so did the main stereo. Would they be coded the same, or do I need to go hassle the dealer and get Ford Direct to produce a second keycode for the DVD system, or what?

Thanks in advance for any help :)