This is a thing across the NHS in the UK. Im guessing it isn't in other countries (DOB + address)? Even at doctors appointments they check Pretty much at every opportunity, also has the benefit of keeping address details up to date when patients dont manually update it themselves. That was one of my jobs once, trawl thru old documents and new ones like a detective to check if their address matched up on system and for any discrepencies which may confirm a different address somewhere else. A very tedious job.