I read with interest tonight that Robert Scoble was having to workaround a new feature in Google Reader and it reminded me that I have been asked a few times recently how we deal with duplicate items ourselves.

When we built our core engine for fav.or.it one of our core principals was that you would never see duplicates of the same content. This is a fundamental requirement because within fav.or.it you read content via ’slices’ instead of just single feeds we have to make sure that any overlap of slices means that once you have read an item within one slice it does not then show up when you switch to the next slice.

For example if you have two slices.

Apple – Which is a slice that contains all posts that mention ‘apple’ within ‘technology’

And

Software – Which is all the content with ‘technology -> Software’

It is very likely that there are hundreds of cross-over posts between these two slices and we make sure whichever order you read them you never get see the same content.

Sharing

As we demonstrated recently you can very quickly share not just single items but whole ’slices’ of content with your friends or the internet as a whole. A shared slice can be a single post or any number of posts and again it is built into the system to make sure that if the user you send the content too has already seen that content they will not see it again (unless they want too)