Then I guess it could lead to duplicate records. Now, whether this is a problem or not depends on the business and how much one cares about data integrity. I work with higher education, so uniquely identifying students and keeping all their records organized is somewhat important. Granted, I don't work in the US, and here we have a unique, national number. So this is covered, except for foreign students. I was curious how this problem is solved in other countries.

The US government doesn't assume that it can uniquely identify a citizen with 100% certainty. When things get tricky, we rely on the judicial system to weigh the evidence and make a decision. Which could later get changed.

If you want to design your system to assume that you can do it, that's your problem. Literally, it is now your problem, and nobody is going to step in to help.