To provide a little more clarity to the answer provided to the OP, with Dish there are two satellites used for the SD (standard definition) channels. The Winegard you have can only point at one of those at a time, therefore, the second TV in your RV can only tune to a different channel IF it happens to be broadcast from the same satellite.
DirecTV has all its SD channels on one satellite (101)so the Winegard can receive them all without re-positioning itself. Therefore, each TV can watch a different channel without the antenna needing to change satellites.