There are two RF-distributions used in Motor homes and trailers, (Well 3 if you get down to it but I do not know of anyone who installs the 3rd save owners)
Many rigs have a "Tv-Outlet" plate, this has a 12 volt outlet, an antenna connector a button and a light,
In this rig the park cable input cable runs to the back of that plate, Center port, the Rooftop antenna runs to the back of that plate, one of the side ports and the 2nd tv gets its signal from the remaining port on the back.
LED on (Button in) is Rooftop antenna, LED-OFF (Button out) is Park cable.
The other method is a box with many buttons, and ... Well, you select the source on a tv-by-tv basis, VCR, DVD, ANT, Cable, SAT and so on
So the answer in both cases is "It feeds both TVs"
NOTE: if installing sat, with the first system Winegard says to use the park cable, unhook it from the plate and extend it to the sat receiver's LNB. I don't like doing this, for one thing it's the wrong cable type. Instead extend it to the sat receiver's TV-ANT-IN jack, then hook the TV-OUT line from the receiver to the port you just unhooked park cable from.
Use nice fresh RG-6 to a handy conneciton point (or to a switch and then to a connection point, MANUAL switch, if you have a rooftop dish antenna, that way if parked under trees you can switch to ground mount)
The truth table for switches then becomes
TV-Outlet ON, Antenna
TV Outlet off Sat ON, SAT
Both TV-outlet and sat off: Park cable
WInegard's method you loose that last option.
Nothing adds excitement like something that is none of your business.
2005 Damon Intruder 377W Radio Active as WA8YXM