I'm sorry, but I'm not in the airline industry and I don't understand what's going on. What is a dual fare? Is this about being W intercontinental but J intracontinental/domestic because there is no W there? I can understand the words in "Dual inventory fares means you have to have inventory in both classes, for revenue control. Otherwise you would be bumped to a more expensive fare in the same primary booking class." but I cannot understand the sentences! Ditto "for P it's easy to say connector is in full J any time".