I have a suggestion.
I do want to search for different topics, but they could share some
results. It would be good to find out, if i already found them.
Of course, i could use the URL, but the URL is not alway unique for a
resource, you could find the same resource at different urls.
I assume, most news come from RSS or ATOM feeds. Within the atom feed,
there should be a atom:id element, this is a mandatory field. RSS 2.0
also has this field (named guid), unfortunately optional.
In my opinion, News-Items alsways should have a URI, and you should
try to compute a Id, if it does not exist (tying to mark duplicates
with the same URI).