@davidfor
I could uninstall the 2nd Kepub 2.3.3 so I have restarted Calibre.
Then I got one Kepub, but the version changed to 2.2.16 with Calibre asking me to update that plugin (that I can't uninstall because Calibre claims that it is a system one).
So I launch the update of the plugin, restast, and get the 2 Kepub again...
I tried to launch Preferences / Output Options before updating to test, and it failed...
Any ideas, please ??