I apologise for the length of this post.

I love the RSS reader in Flock - it's one of my favourite features, and the presentation on My World and everything is miles ahead of anything else I've seen.

However, for the first time I've come up against an issue with an RSS feed.
Specifically, the Last.fm Events Recommendation feed (at this point, can't resist mentioning how much I would love integration with Last.fm!). You can find it at http://www.last.fm/home/eventrecs if you have a last.fm account.

I don't know how familiar you are with Last.fm, so I'll just outline the idea of the Events Recommendation - based on all the artists you have listened to, it creates a list of upcoming gigs in your area. Now just the other day, I noticed the rss button in the corner, and got quite excited about it - completely automated gig alerts for every artist I've ever listened to! Wow!

It was great at first, instantly listing over a hundred events. I went through them, picked out a few I might go to, and closed the feed, very pleased with my discovery. Next time the feed refreshed, there were 60-70 new events!
But when I looked at them, I realised they were the same events I'd already read. This happens every time the feed refreshes, no matter how many times I mark everything as read - the same events come up again and again.

Now, I think I can guess what is happening. I may be completely off the mark, and I don't have that great a knowledge of rss feeds, but here is the best explanation of the problem as it appears to me.

Last.fm recommends a lot of events at once - around 160-70 for me, but probably more as you listen to more artists. The nature of the feed is very dynamic - the events are listed by date on the page, but this isn't necessarily the order they appear by on rss. I don't have the jargon to explain it properly, but every event is listed on Flock as being created at the time it was synced. This makes sense - if I listen to a new artist, and they are playing near me soon, then their gig could appear at any point in the list. I haven't explained the idea very well, but it means that each event exists as a constantly new item. (It's probably easier if you check out the feed for yourself...)

However, the Flock RSS feeder automatically deletes old rss content that you have read, imposing a limit of 100 stored items. Usually, this is fine, because most feeds update chronologically (and if you do want to save something, Flock gives you the option!). However, this Last.fm feed is an exception.

Because of the dynamic nature of the feed, and its size, the same events get thrown back at you when this 100 item limit is in place.

This is a horribly long explanation, so I'll stop there, but if I haven't explained anything properly, then let me know and I'll have another go.

If I am right, then it can be quite easily fixed, by removing the automatic limit on the number of items allowed. Ideally, you could allow the limit to be user-set, or optional, adjustable for each feed.
I really hope you can do something about this, because it is the only fault on an otherwise perfect RSS feeder, in an otherwise perfect web browser.