TIL that some regions have more than one supply caches.

[yollarbenibekler]

In PV I've found two supply caches (the one you'll find with the handheld shortwave radio, the yellow signal). I don't know if it's a feature or a glitch. So, if you've found one supply cache and think that's all, I suggest you keep checking your radio in the event of the aurora. 

Happy hunting, everyone!

[Leeanda]

It varies on the region, @hozz1235 has written a list somewhere.  

[Glflegolas]

I think most larger regions have at least two supply caches.