Looking on the demo site right now I'm not seeing any duplicates in the recent content feature. When making multiple edits in a row within a short time interval it could be a timing issue because the search index is not updated instantly. There is a task which processes the indexing queue on the first loop it deletes items based on the key and then on the next loop it indexes the updated content for that key. But occasionally duplicates for a key can happen in the search index if edits happens in short rapid succession. If a duplicate does occur for a given item it will usually get cleared up after the final edit when it processes the index data again.