Honestly it seems like this is a common issue with many schools. I've seen this reported on SDN frequently in different school threads; I think Duke was famous for it last year when it occurred with people who were rejected post-interview. It's probably an issue with whatever software they are using - rejected applicants are probably in a pool, and if the pool isn't updated to reflect the people who were already rejected, they probably get onto the list for the next round of rejection emails.
You are understandably upset, but I doubt there are many schools that have not had some sort of issue relating to technology with respect to the applications process over the years. This year Tufts had a security breach where students were automatically logged onto accounts that were not their own, Baylor has a whole section on their website on what to do if their Paypal portal fails (this is frequent enough to merit a section on their website), some schools don't mark people as reviewed until months after they are complete, some schools send rejections even if you don't complete a secondary, the list goes on and on. Some schools are more communicative and some schools are less communicative, and it seems that each individual applicant has a difference perception of that school's process based on their own expectations/past experiences/experiences with the school itself/experiences with other schools.
