Not sure what the mystery controller might be. I use Unity's built in input manager for the controls, I don't think it can show the name of the controller it's actually reading. Also I'm not a Mac user myself so I'm not very knowledgeable when it comes to Mac specific questions. At least on Windows joysticks/controllers that are being detected usually shoes up as a generic HID device in the operating systems device manager. Perhaps you could try to temporarily disable the last thing that you suspect might show up as a controller (although I wouldn't really recommended it if it is indeed some kind of security chip...).
My guess is it's the xbox 360 controller driver that doesn't get picked up as a joystick in Unity's input manager. Did you try to connect the controller without any extra drivers first? (A lot of the time generic gamepads automatically connects as joysticks, at least on Windows).