Magento 1.9 CE has an url rewrite issue. Magento create the extra entities (duplicates) in 'core_url_rewrite' tables on each reindexing of 'Catalog URL Rewrites'. This Magento module targets this issue and prevents creating duplicates in 'core_url_rewrites' table. However, if you have the running Magento installation, you probably have the duplicates in the database. This repository contains a dedicated Shell script that allows you to remove the duplicates from the database. If you don't want to remove all entities (this makes sense for SEO reasons, since the existing URLs might be cached by search engines) you should use an additional argument --except 'number'. With this additional argument script will delete all records except last 'number' rows.