Please put three backticks ````` before and after your terminal output (like the error log output).
What desktop environment is this, Budgie or one of the others?
From what you've described, it seems like CUPS auto-added the printer when it was first discovered, then tried to auto-add it again, and failed (since it was already set up).
Have you tried re-enabling the printer through the CUPS web interface (not the system settings)? That might work. It would be in printer administration.
This week, an updated version of CUPS is being tested in unstable. As mentioned, the current version is very old. If all goes well, the updated version will be synced to stable in the next sync (usually Friday). That may help with some of these printing bugs.
