If a port name ends with a number that coincides with the port number, the number is stripped from the name.
Example:
If I have two ports named (their real names) "Port 1" and "Port 2", they will both be reported as "Port" in the port list and hence cannot be used.
Edit: The problem seems to be a macOS problem only. I can't see that port names have any numbers appended on macOS, causing the real port name to be truncated if it ends with the same number as the internal port number.