basicConfig will register a handler too, and it's possible to have many. See log.handlers for the ones currently registered, it's a plain Python list that you can clear to get rid of them.
Autodesk Maya is special, it runs the equivalent of basicConfig under-the-hood at startup. Which means that you always see these messages whether you want to or not. You can remove handlers, and edit them despite this.
Standalone Python doesn't have any handlers registered, and needs something like the above.