I have exported all content from a live WordPress site and Imported it into a local site on my computer.
I changed all the category names and re-assigned new categories to each post.
My question:
If I export all content from the local site and import it into the live site will it overwrite all content or create duplicate content?
Should I clean all content from the db tables (after a db backup) prior to the import?
What importer/exporter did you use? The Wordpress Import/Export tool?
Unless you have a complicated set up with custom post types, pretty sure it should export the categories and tags as they are.
Using the Wordpress import/export. I know how it works, my question is if I import the same content (post, tags, pages etc.) that already exist, will it overwrite the existing content applying the new categories or will it add duplicate the content?
All the content was assigned to different categories. I wanted to break it out into sub-categories.
Example:
Post were assigned to the wordpress category.
I created sub-categories, menus, tutorials, plugins etc.
(This was also in conjunction with creating a new theme)
This would give me the ability to list sub-categories in the main menu in a dropdown instead of a single category.
I know this is the long way around doing a theme, but I also wanted to change the way the post were displayed.
I guess the only way to find out is to just do it.
AFAIK it won’t import posts that already exist. (But don’t quote on me on that)
No harm in setting up a local test environment to try it 
‘Sigh of relief’
It will not duplicate any content that already exist.
It did duplicate the custom menu but that was easy to fix by deleting the duplicates.
In this case that’s good because the old theme was using wp_list_categories and I am switching
to wp_nav_menu with the suckerfish menu.
Thanks for your replies AussieJohn.