I don't have time to test this at the moment, but It keeps bugging me not to know the answer.
Suppose I subscribe to a message on an instance of CustomContentPage (subscriber) to CustomContentPage2 (sender). Suppose I push two instances of CustomContentPage on the navigation stack and then an instance of CustomContentPage2. When a message is sent from CustomContentPage2, will it be run on both CustomContentPage instances or the one that comes before CustomContentPage2? To prevent the message from being processed by both pages, what should I do?