It sounds like you ‘may’ have created two separate Sonos Household/Systems on the same WiFi network possibly using different Sonos Account credentials.
The second ‘Port’ with its status LED flashing different colours sounds like you have put it into Diagnostic capture mode by long pressing its join button etc.
I would perhaps try this…
Power off the Port that is not recognising your account login credentials.
Reboot/power-cycle the Port that is ‘possibly’ in diagnostic mode to see if that clears the flashing status LED and if so, then reset your Sonos App and connect it back to the ‘existing’ system and select that Port. See if that then allows you to sign into it’s assigned Sonos Account and that you then see it okay in your Sonos App.
If that all works so far, then factory reset the first Port that is powered off and add it to your current system using the ‘Add Product’ feature in ‘Settings/System’ in your Sonos App.
Hope those suggestions work for you.👍