A lot of state DMVs and other government offices apparently use name + birthdate as a "unique" identifier, which works about as well as you'd expect. It doesn't usually cause problems, because both people are accepted as 'real', but it's alarmingly easy to end up with someone else's license suspensions, voter registration, or even credit score.

https://www.theguardian.com/us-news/2017/apr/03/identity-the...