I think it would be quite easy for Disney to modify their ADR system to simply not allow overlapping ADRs... if they cared about that.
I disagree....because it does seem like Disney has tried that. For a while they would cancel one or both of your reservations if they were too close together in time. Then people started using different email addresses, phone numbers and putting some reservations in spouse's name or even the kid's names. And they bragged about it on DIS and other boards. So, how do you track duplicates when in less than 5 minutes you can make a new email....most people have a half dozen phone numbers in their family (home, work, everyone in the family has cells, relatives even since no one from Disney ever calls it anyway). And names...well, if you run out of those travelling, now that you can make the reservations online you simply use variations....John Doe, J Doe, JL Doe, etc.
Now...credit cards start narrowing that game playing field....sure a lot of families have a couple credit cards, but relatives may be a little less willing to give you their credit card number. But even so, it doesn't stop people from making duplicates. Between personal and business cards, my husband and I have 4 credit cards and 2 debits cards....so we could potentially make 6 reservations. BUT....by threatening to charge us rather substantial amounts for not showing up, hopefully less people are going to bother making duplicate reservations. Because, the reason most often stated is that they don't know what park or when they'll be hungry, etc.....so since the same could probably be said 24 hours ahead of time, the duplicate will have to be cancelled before you how where you'll be and when you'll be hungry.
Disney can't track this by ISP, because many people have the ability to change their ISP...and many people use an ISP that is the same as many other people not related to them. Many companies giving away freebies have tried tracking by ISP but it only slows down the computer savvy....and a little research online and anyone can be savvy enough.
So...charging makes sense. It gives a huge incentive to NOT game the system. No unwanted charges. There are still people who are already posting how they plan to get around it, so it won't stop everyone. The diehards will still make the reservations with their credit card, then stop that credit card and have another issued. Seems way way way too extreme for me, and too much hassle just for a reservation, but then I can't really see making duplicates anyway. And a part of me hopes if they go ahead and do that....since opening and closing credit cards can damage your credit scores, that they enjoy the higher rates they'll pay for mortgages, car loans and just balances on their new cards. neener. Since my score is in the coveted 700's no reservation and not even a large fine for being sick, tired or not hungry is worth messing with that. My current car loan is 0% for 5 years.....that a lot of fines that I'm saving, lol.
As always, this gaming really hurts those of us who do our best to keep our single reservations, and those who regularly game the system, will simply find ways around it, while we will end up paying a fine for being tired, not hungry or whatever. I just wish we could have seen this coming a little more clearly and instead of just gasping in frustration at the audicity of those bragging about, we'd have had the foresight to blast them out of the water and plea with DIS to erase those posts so that others didn't get the idea. But, not sure that would have mattered, as gamers always game, whether they have bragging ability or not.