This is surprising to me. At the hospital where I worked, everybody was assigned a medical record number. It was possible (in fact, I saw it done several times) to change the name of the patient, and even combine multiple patients into one (useful for drug seeking patients who claim to be multiple people on different visits). A common case was with newborn/pediatric patients. A newborn was listed with a system name of <Mother's last name>/Baby <Boy|Girl> with an optional A/B/C for twins/triplets/etc. If that patient was later admitted in follow-up (for example heart defects which required multiple surgeries over time to fix) their actual name was then used.

I guess the issue is that the future is not evenly distributed.