How do I explain the catcher situation in categories 5x5?

It looks like you can start two catchers (having two catcher spots on the lineups page), but when I look at the rules it says that Ottoneu isn’t a 2 catcher league. What exactly does that mean?

My guess is that you can start two catchers on a given day, so that you can get to that 135 catcher max, but I want to make sure I explain this to my league accurately. Any other tips or strategy regarding catchers would be useful.