I have the same setup in my 99 Windsong, there are 2 switches both having 3 positions. The reason for this setup is as mentioned before the 30 amp service.
When pluged into land power you can run only 1 AC at a time, when using generator you can use them both because each AC is wired to seperate legs on the genset.
When pluged into land power; Both switches up is rear AC
Both switches down is front AC
When using the Generator Both switches up you can run both front
and rear at the same time.
Middle switch position is no function, I
use it as a off position when I'm not
I hope this helps you..