This is impossible isn't it? You can't have a meal booked at a different place for the same time slot (I think it's a 2 hour window?).
The only way I could see doing this is booking a dinner at 3pm, 5pm 7pm and 9pm, for each park, for each night. If that's the case, then yes, that's insane.
Oh, it's most definitely not impossible. There are a lot of ways to go around the system. The system only makes you cancel if you have another ADR within a little over an hour of the one you are trying to book. As someone else said if they had another MDE account or someone else in their party did they could get around it that way. Also, I've had to book an ADR over the phone with the automated system and it doesn't add the ADR into your MDE automatically that way. When I linked the one I booked over the phone it forced me to cancel but if I had never linked it I would have had two reservations at the same time.