With this Joomla! plugin, you can assign multiple categories for K2 items. This plugin leaves the K2 core and the template files untouched. The categories are also displayed at the backend and are countable.
# [Bug Fixed] The total calculation of K2 items is not correct where these displayed on category list. This affects only the k2 subcategories.
# [Bug Fixed] Call to a member function isSite() on null [Thank you, Gerardo Marín]
# Minor fixes and improvements.
# [Bug Fixed] When saving a subcategory the items removed from the #__k2_multiple_categories [Many thanks to Шульга Евгений]
# [Bug Fixed] Class 'Factory' not found after trying to migrate from the "Additional Categories for K2
Joomla! K2 Plugin"
+ Watchful support.
# Minor fixes and improvements.