With this Joomla plugin when we use option "Save as Copy" on a menu item, all the module assignments will be copied as well. That includes all the modules assigned to the original menu item as well as all modules that have original item in "Show for all except selected", in that case the copied item will be added to exception list as well.
Download latest release and install it using Joomla's extension manager.
GNU General Public License version 2 or later