node->created date is reset to arrived date on second refresh

If the feed has 'Update existing feed items' turned on:
On the first refresh/retrieval of the nodes, the dates are correct publish dates from the rss.
A little later, requesting a second refresh, all the node->created dates are overwritten by the same arrived date, completely destroying the sort order.
feed: http://www.clipsyndicate.com/rss/feed/1778

Btw, I have noticed a Yahoo Finance feed that was creating the same article over and over as the description was being slightly edited at Yahoo. The title was the same, so shouldn't 'Update existing feed items' be taking care of this, as opposed to creating new nodes for every incoming edit?