Mercedes Spec Anomaly

[Greenmantle]

Last night I did a Data Card check on a vehicle I am thinking of buying.
The Data Card says option 864 "Rear Entertainment (2 Screens)
When I look at the pictures I see the MB tablet / ipad holders instead. No wiring.
What is going on here?
Is the wiring hidden in the chairs, Could I replace tablet holders with the screens without breaking the bank?

Cheers
John