I really don't see how Disney is wrong for following their policies. I, for one, am glad that they are taking a more active role in doing so than in the past. Just because people never got caught doing this before doesn't make it right.
I will warn you. I have a lot more to say about this in light of the comments I have read:
I still don't get how the OP can claim that she didn't have so much of a hunch that this could have been wrong, against policy, problematic, whatever. If this was really the case, then why were you so careful to clearly explain your situation so many times?
You can make multiple bookings for a two week period before you put down a deposit so the original CM wasn't completely wrong. However, I think it is wrong that this CM gave you such bad information and by all means complain about that. I hadn't realized that this wasn't your idea but you were simply following Disney's instructions. That's a different case entirely. I thought you said in your OP that you made two separate reservations not one with the same CM. Maybe you could clarity.
I agree with jckdisneybound. Why didn't you just book one room for five people regardless? Then if your daughter didn't come you could just let them know there would only be four of you or switch your reservation to a different resort then.
Clkelley, you can change your resort at any time. This is not a problem. You don't need to make multiple reservations. You simply change your existing one. No, Carolyn, that doesn't bother me and Disney doesn't care because they don't lose money and it doesn't take a room away from anyone. I'm not talking about discounts at all. That's a completely different topic.
Claiming ignorance to the reservation policy doesn't make Disney wrong for cancelling one of your reservations. WDW is not required to read all the small print to every customer before they make a reservation. Stitch Inside, if you ask for some literature about this policy, I'm sure they'd be happy to send it to you. Also, if you pointedly ask them what their policy is about multiple booking, I'm sure they would be able to read it to you.
Ali