I think it largely depends on where you will be camping and the type of camping you will be doing. For instance, I live in the southeast and wouldn't consider an rv without the second AC.
That said, most units have the option for two ACs. The unit you are looking at may have been ordered with one but a 2nd can likely be added. This could be a negotiation point for you with the dealer. They can likely add the 2nd, just be careful that they do it in the same way that the factory would. Ie if factory is ducted, make sure they add the exact same type as the factory would and that it is ducted in the same way. Don't let them cheap out.