I have a development site and a live site where the database differs on 2 weeks(On the development side has been added between new Posts and Pages). What I want now is to export the posts and pages from the live site and import on the development side but without to override the newly created posts and Pages. Is it possible to achieve this with the standard wordpress import export plugin?
wordpress import function
The import tool in WordPress doesn’t overwrite your posts and pages, it just adds them to your database. You can read about it on the following topics:
http://wordpress.org/support/topic/wordpress-import-1
http://en.forums.wordpress.com/topic/will-import-over-write-existing-posts
However, it’s always a good idea to backup your database before you do it.