your right, neither would see 240 volts, but neither would have the correct voltage either.
In the real world the loads are rarely equal, but they are often close enough that damaging over voltage does not happen.
My own homes service lost the neutral at the utility, I put my recording meter on one leg of the service and had lows of 80 volts and highs of 140 volts, I did not lose any appliances or lamps.
The only way you can actually get a 240 volts on a 120 volt circuit is if the other side of the circuit has a direct short with no resitance.....a very unlikely scenario.
By the way....welcome to the forum.
