Some tumblr feeds I am subscribed to double the first 2-4 images (sometimes more, but it seems usually to be the first 2-4), then display 5+ only once. I tried looking at the RSS myself, but nothing jumped out at me immediately as being wrong?
Example feed: http://toastyhat.tumblr.com/rss
Example post: http://toastyhat.tumblr.com/post/137017205359/the-amazing-kukutjulu-1-2-3-4-5
This isn’t a burning problem, just an oddity that I wasn’t able to track down the cause of, and so was interested in. I’ve only seen it on tumblr blogs as far as I know of, but then the majority of my subscriptions are tumblr blogs, so it’s possible it happens in other ones that I haven’t seen yet.