Plugin update notification

I don’t understand why I sometimes get plugin update notifications (“a new version is available”) when Glyphs starts. Those plugins were installed through the plugin manager, shouldn’t they also update through the manager automatically? When I look in the addon preferences, the updated plugins are marked:

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… but the Download button takes me to the website (GitHub repo) of the plugin. How could I know from this that actually I should find the cloned repository in the Glyphs application support folder and update the repo there? If I don’t know this and download the plugin from GitHub, and install it directly in the plugins folder, the repo clone will still be there, orphaned, in my repositories folder.

This is a bi of a mess. The Plugin Manager and the Addons preferences don’t play well together.