Hi,
I would expect only one CMC-PD MIDI Port. You can get more ports if you would get multiple devices connected. Or maybe you could get more ports, if you had connected the device to other USB port.
Cubase shows all available MIDI Ports on Windows (on Mac it does show only currently connected MIDI Ports). So if the system recognises multiple of them in the past, the may remain in Cubase. I would just try out which one is the working one and keep this one only.