How the hell is it that two belts, once unified become 'ununified' anyway? Is it only through retirment and then the assosciations chossing different fights for their titles? Can't see how a unified champion could ever lose one belt but not the other.
The organisation also has to sanction each bout as a title match so sometimes they choose not to so the belts can't be up for grabs. Sometimes they don't make the weight but have the fight anyway so the title can't be on the line etc.