No it's not.
I have 2 NVIDIA HDMI Output devices (port 0 and port 1). I would guess they are for the hdmi and thunderbolt ports probably?
I also have Speakers (Realtek HIgh Definition Audio) and Realtek Digital Output (Realtek High Definition audio) as audio devices.
see attachment bellow:

And as logic suggets, Speakers are used for speakers and headphones, whereas Realtek DIgital Output is used for digital output.
I have no problems getting the sound to work, but as it seems, the realtek Digital Output device appears to always be active, (i.e. can not detect whether a cable is plugged in or not (see hdmi devices as reference)), and because of that windows will not auto switch to and from that device, and I have to manually set the default device each time I want to change the output.