Not sure if this is a Windows-specific problem… if I copy a skin directory (under %APDATA%\Kodi\addons) and rename it, as suggested in the skin development intro, it will not show up in Kodi as a new skin that can be installed. I also tried changing the id in the new addons.xml file to something unique, thinking that may resolve any conflict, but still no joy.
Is this something you can no longer do under Krypton? Or does something else have to be changed to allow the new entry to appear?