IMHO, it would be beneficial to introduce a new database field associated with items: last-added. It would contain the timestamp of the last attempt to add this item to the database (think duplicate rejection). Sorting all items by that field instead of their upload timestamp would be less confusing because even if the upload you're attempting to perform is a duplicate, it would still be up front and seem to have worked.
I would even go so far as to suggest not informing users of a duplicate if this is implemented. It's no severe error, the action they attempted to perform (bring something up front) succeeds anyway and they can see it on the front page, tag it on IRC etc.
IMHO, it would be beneficial to introduce a new database field associated with items: last-added. It would contain the timestamp of the last attempt to add this item to the database (think duplicate rejection). Sorting all items by that field instead of their upload timestamp would be less confusing because even if the upload you're attempting to perform is a duplicate, it would still be up front and seem to have worked. I would even go so far as to suggest not informing users of a duplicate if this is implemented. It's no severe error, the action they attempted to perform (bring something up front) succeeds anyway and they can see it on the front page, tag it on IRC etc.