The booster should be on for both tvs. If wired correctly it shouldn't matter if the other tv is on or off. Some tv tuners are more sensitive than others so if your signal is weak that might be issue too. If you have cable and sat connections in bedroom the manufacturer may have crossed these two so try the sat connection. Can be easily corrected by removing the wall plate and switching if that is the case.
2015 Ford F150 Platinum 3.5L Ecoboost
2015 Rockwood Ultralite 2604WS
No longer mine: 2006 Rockwood Roo 23SS