The problem with duplicated menu items may appear when you pressed “Import Demo” button several times during demo data import process. You can sort this out in two ways: either using WP Reset plugin or remove duplicated menu elements manually.
The first way by using WP Reset plugin is automated but it will remove all your custom data from database including posts, pages, menus, theme options etc, deactivate installed plugins and activate default WordPress theme as you have it from the beginning after WordPress installation. That’s why you need use this method carefully as you’ll have to start your site from scratch.
To install WP Reset plugin go to Plugins > Add new > type WP Reset in search field > press Install Now button and then Activate button.
After you installed the plugin go to Tools > WP Reset and follow the plugin instruction.
As it was said above the other way to get rid of duplicated menu items is to remove them manually. To do this you need go to Appearance > Menus > select your menu and delete all duplicated elements. This method takes a lot of time but you won’t lose all of your customizations and content as by using WP Reset plugin solution.
