Could be copyright traps to detect unauthorized copying of the map:

https://en.wikipedia.org/wiki/Phantom_settlement

So the towns that show up did exist at one point in the 1800's and early 1900's for a couple. They were towns in the past, but aren't anymore. So I'm not sure they're paper towns. As I understand it, those never existed at all.

Map Men have a fun take on it: https://m.youtube.com/watch?v=DeiATy-FfjI

(Their whole series is brilliant too!)

Four of them in basically the same spot?

If they're all copied, then they've got a pretty good case that they'd been copied, and it couldn't have been an accident.

If you can copy one fake data point by accident, you can copy four.

On the other hand, having such an exact match is clearly not a coincidence even if there's only one.

So either way I don't see the value in having four.

Good one. These are the real easter eggs

Various maps ingest almost random data - around where I am the street maps (plots) are about 50 feet diagonally off.

It’s entirely visible if you overlay satellite with the map, but it’ll probably never be fixed.