I've been keeping up with the changes, so feel free to ask me anything. It doesn't mean that you can't use more than one of your MBs or cards. If all of your cards and MB's are attached to your profile in your MDE account, meaning that you see them all listed when you look at your profile, then you can use any one of those bands or cards to enter the park or for fp+. That means you can use your pink band in the morning then use your blue band after dinner.
What the change really means is that you can't use a fp+ that was booked using a ticket belonging to someone who did not enter the park.