1) Yep, sorry.
2) But, if lots of people make duplicate ressies, there are less ressies available for others who might want that ADR.
. . . this is why the Dining Reservation System was changed and now checks for ADR's too close to each other
. . . and, even more changes are on the way
3) I like to ask, "If you wanted an ADR and couldn't get it because someone else had a duplicate ADR, how would you feel?".
4) Sure, people say they will cancel soon, so others can take it, but many folks try to plan their vacation and meals well in advance.
5) If there are unavailable ADR's, their plans might have to change significantly.
NOTE: Regarding the 180 day, or 180+10 day, booking for meal ADR's.
For Disney: It is nice to know well in advance of restaurant occupancy/demand, and be able to predict revenue. ANY business would like this.
For Guests: Many people do complain about having to planning so far in the future, but many others like the idea of knowing they have the reservation, or have ample time to re-plan. In the past, people would be getting close to their vacation and then have to scramble for an ADR. This changed a lot of touring plans without a lot of time to adjust. Now, they can get their planning done and just anticipate the vacation. So, it is a toss-up, but Guest Surveys show most folks want the assurance of the ADR.