Podcast aggregator downloading old podcasts

I'm using Juice as a podcast aggregator, every now and again (quite rarely) it suddenly goes crazy and starts downloading old podcasts which I've already heard.

I don't think this is a problem with the feed because it just happened for quite a few feeds (from BBC, NPR and Nature).

Do you know if this is a known problem with my aggregator? (if so what alternative would you recommend?)

Solution 1:

I have seen this happen with podcasts and other RSS/Atom feeds (including feeds of Stack Exchange blogs). From what I have seen, this is probably due to the publisher of the podcast or feed has made some change to their system that has accidentally made a change to the unique identifier of each item. The effect of this is that an aggregator does not recognise that some items are the same as previously seen ones, and so it treats them as new items.

Unfortunately I see this quite often. I understand that if you see it on multiple feeds that you would suspect that Juice is at fault, but it may be feeds that have been broken at almost the same time.