Stuff like this seems like it might happen in any low-quality identity system (possibly aided by customer support who can't possibly be blamed for just trying shit and seeing if it works) regardless of whether it's based on some hacky version of telephony. I often pick up prescriptions for my wife at CVS, so we had her account linked to mine, but after we moved for some reason they had trouble filling one of my prescriptions, and I had to spend a while on the phone with them. They had filled it at the CVS near our old address but for whatever reason their computer system was not able to cancel that like usual and fill it at the one we had switched to, and eventually whatever "fix" they did somehow made my wife's phone number start receiving all of our notifications. Even more confusingly, a prescription I started on later didn't show up in either of our accounts, but it was still getting filled somehow and would be ready when I went there. After around a year of this something changed in their kiosks for putting in your info to get your prescriptions listed, and suddenly I couldn't get it to show up there either and would need to spend an extra 20 minutes hashing it out with them for a couple months. The most recent time I went there, they finally told me that apparently I had two separate accounts: one at our old address (which I hadn't lived at for over a year) with my phone number, and one at our current address with my wife's phone number but the common prefix nickname version of my first name (think like "Will" for William or "Ben" for Benjamin). Because it was somehow on an account with my name, my phone number, my old address, and literally no email address at all, I couldn't log in and view it in the app, and because it would "standardize" my name to the account that had my current address, I couldn't access it on the kiosk. It seems that whichever customer service rep I talked to literally duplicated my account, put my wife's phone number on it, moved all of the prescriptions we had at the time over, and associated my email address with it, but then left the old account otherwise intact and just waiting for some database quirk to unexpectedly end up assigning a new prescription to. The part that surprised me the most was that the person I talked to at CVS was entirely unfazed by this and had a standard process for merging the two accounts, which means that this apparently happens a lot.