Merge Identical Postings

Some feeds (like AP headlines) repost their articles several times a
day often with little new material. This means that in days i can have
over 150 postings from them but only 20 separate articles. The Reader
should autimatically merge all identical posts (from the same source)
and display only the newest one -and when that is read they should all
be marked as read. It sure is a pain scrolling through hundreds of
duplicate postings.