I've been running SVN for a while now, generally I'm quite satisfied with it. But recently it's giving me trouble with some podcasts. More to the point it keeps detecting some episodes as new every time I scan. I believe it's caused by one URL for a file existing in several places either in one feed or in several feeds.

Examples:
Two libsyn based podcasts I listen to have "Welcome to Liberated Syndication" as their first episode. On every scan one of these two will read "Welcome to Liberated Syndication" as a new episode. It's happened to me with both and I can't see any reason or pattern that determines which of the two will be marked as new.
Escape Pod (Sci-Fi short-fiction podcast zine) episode 61 was also posted to I Should Be Writing, the author's podcast, which I also listen to. It will read new either in the Escaped Pod feed, or in the ISBW feed every time I scan.
One further podcast gives trouble because episode eight has two enclosure tags, one with the URL for episode 8 and one with the URL for episode seven. Either episode seven or episode eight will scan as new every time. This instance is clearly a problem with the feed though, so I've notified the podcaster in question.

I think this may be an old problem spreading further because of the "* Support non-chronologically ordered podcast feeds. (BR 119911)" mentioned under bugfixes in the changelog. I had a trouble with Escape Pod 61 before, when it was the most recent podcast in two feeds, but that went away instantly when Escape Pod 62 came out. Now it's not going away.

It's a known problem, we're working on it.