if you go to control panel, sheduled tasks, you will find a Merge Duplicate Resources Task. Also under Reports - Notification Server Management - Server - Resource Reports, there is report called merged resources.
Make sure the "NS.Merge Duplicate Resources.{dfe04fea-d71a-438f-b40e-a8ecd01304c7}" is running, By default it runs every day at 6.15 AM.
Hope this answer your question.