[DSMan195276]

> But what would be the use case of re-opening your own files in this way, that dup() doesn't cover?

Well you can't `dup()` an fd that you don't already have, this would let you do it. Assuming I understand the behavior right it doesn't have to be the original program calling `open()`.

If you're running a separate process and trying to debug another process that's running by peeking at its fds, then being able to just `open()` them is easier and less invasive compared to the alternatives for getting a dup'd fd (Ex. force the program to call `dup()` itself and then send the fd over a socket or something).