So, the way I understand it, when an RV has a 50 amp power system designed into it, it's essentially two separate 25 amp systems. The high power applicances are split up, so the two AC units will be on the two separate systems. When a 50 amp is adapted to a single 15/20 amp house circuit for 115vac, it's not supplying both circuits with 7.5 to 10 amps. It's supplying either one or the other circuit in the RV with 15/20 amps of 115 volt power, and the second circuit gets nothing. If that second AC unit is on the second circuit, it won't get power. Anything that is assigned to the second circuit is not powered, and which appliances and outlets that might be is up to the electrical engineer who designed the RV electrical circuits, and how they shared the load.
But there's more to the story. While your one roof AC might be on the circuit you see has power, and it may turn on, it is wise to check the voltage of that circuit inside the coach. If you are on the end of a long extension cord in addition to your RV's main power cord, going through several plug/receptacle combinations, you will see a voltage drop. The lower that voltage is at the coach, the more likely your AC compressor and fan motors will run hot. The lower the voltage, the hotter they run, and the sooner they fail. Running the AC and, say, a microwave at the same time on a long extension cord to your 115 volt 20 amp circuit in the garage is going to drop the ultimate voltage down even further. Personally, I would not run anything below about 108 or 109 volts, while these appliances are running.
2006 Jayco Seneca 34SS
2006 Jeep Wrangler Unlimited Rubicon Toad