I am not familiar with your unit, but have had other Jayco 5'rs with similar specs. It is not uncommon to connect two tanks together internally. Because of this, there might be only one valve and one indicator light as to how full they are. If tanks are not tied together, say when one grey water is for the bathroom and one is for the kitchen, then you would have two separate valves and indicators. If you had one bathroom, I would expect their tied together, separate bathrooms might require separate tanks and valves. It is my understanding that when tanks are tied together, they are connected at the bottom and water raises and falls together. This is to get the most tank capacity at all times. Hope this is correct for your situation.
2015 Seismic Wave 310
2013 Chevy Silverado Crew Cab w/the marriage made in heaven, "Duramax & Allison".