That about describes it. I do a podcast and recently changed servers so I changed all my URLs. Today, I was going through my rss feed and I noticed that there were two enclosures instead of just one, even though the number of links in each post stayed the same.
It seems that when you edit a post and change the URL to a file, WordPress does not update the meta table and delete the old entry. I got around this by doing it myself, but has anyone else noticed this?