More common than you might think. When I lived in a remote Amazonian village in the early 2000s, a local teacher was named Hitler (his given name). This area probably barely had contact with the capital in the 50s, let alone Europe. It wasn't uncommon to choose a powerful or famous name, and Hitler was probably just someone who they knew changed the world.

There were other interesting names still being given too. My favorite was a baby named Shakira Marley while I lived there.