That's very strange indeed. I just downloaded the plugin from both this thread and from plugins.calibre-ebook.com and confirmed that both files are identical and provide version 2.2.20:
Code:
% shasum -a 256 220565.zip KePub\ Output.zip
6b94b634a8594ae0a70bb1c2da4a84f6a1f0f7e8342b793d3e68c07d12e1e284 220565.zip
6b94b634a8594ae0a70bb1c2da4a84f6a1f0f7e8342b793d3e68c07d12e1e284 KePub Output.zip
The first one is from plugins.calibre-ebook.com, the second is from the first post of this thread.
Could you please try removing all of the instances of KePub Output, then restart calibre, then install it using calibre? To do that, in case you don't know, click on
Preferences, then under
Advanced click on
Plugins, then
Get new plugins. Make sure that "Filter list of plugins" is set to
Not installed, then enter
KePub Output in the "Filter by name" text field. You should see one item in the list, and the
Available column should read "2.2.20". Select it and click
Install, then follow the prompts and restart calibre.