Unless the circuit breakers and wiring is changed between the inverter and circuit breaker boxes, the double buss is not used. This keeps all of the inverter powered circuits on one leg of the power into the coach. This is no problem for the inverter, but puts a larger load on one of the 2 circuits in the main panel when running the AC's and anything else powered thru the inverter.
When I installed mine, I was on the road and had to keep it simple. I just ran my original power to both of the inputs and only used one output. When I get time, I plan to add 2 two pole circuit breakers and split the input and output between the 2 separate 120 volt legs at the main circuit breaker panel, to help spread the load.
2007 Limited SE 40fdts
Las Vegas, NV