Maybe there are people like me who can't justify the time off for both Dopey and Dumbo, but I can make Goofy and Dumbo work? Also, they usually have less than 1,000 Goofy slots, so more limited supply than the other races.
My wife did the exact same thing - wasn't going to register but then just opened the registration about 15 minutes ago and got it for the 10K before it was gone...
my sister-in-law got in immediately and registered her and my brother, called me, but I told her I had a 5 minute queue, that didn't work, so I called her back, she got right back in and registered me for the Full. I love Disney IT.
He has to send a message to RD. They have a no-cancellation policy but they've made exceptions for people who want to upgrade their registrations (i.e. marathon to Dopey). Not sure if they'll do the same for someone who's double-registered but the only way to find out is to ask.