
Originally Posted by
dbltoe
Looks like the admin/includes/functions/extra_functions/stats_monthly_sales.php is the culprit.
It checks to see if the stats_monthly_sales page key exists and adds the extra report menu item. It apparently does not check to see if the specific menu item (FILENAME_STATS_MONTHLY_SALES) already exists. Thus your second menu item is registered in the admin_pages table of the database.
You can use the phpMyAdmin to search the table for FILENAME_STATS_MONTHLY_SALES and delete one of the entries. That should fix it.