How to Fix Duplicate Posts in RSS Feed Readers

Do old articles suddenly reappear as new or updated in your feed reader, even though nobody changed them? These duplicate posts in RSS feed readers are usually caused by small automatic changes to feed content, duplicate feed formats or changed post IDs. This guide explains the causes and how bloggers and readers can fix them.

Quick answer: Feed readers flag a post as new or updated when its unique ID or content changes. Automatic additions such as related-post lists, changing ads or share counts in the feed can trigger this. Keep feed content stable, keep post IDs unchanged, offer one main feed, and limit how many items your feed shows.

Our experience with duplicate posts in RSS feed readers

Many readers asked me in 2006 whether I saw old posts appearing as recently updated in their news aggregators. I saw it often, both in my feed and in other blogs that did the same thing: I had added related posts to my feed.

The Related Entries plugin found keyword-related posts for each article and listed them at the bottom, which helped readers find more content and increased pageviews. But when I wrote a new post about, say, Google AdSense, the plugin updated the related-posts list in several older AdSense posts to include it. Those minor changes altered the feed output for older items.

Some readers, such as Bloglines, were very sensitive to these tiny changes and showed the posts as updated, while Google Reader largely ignored them. Bloglines also noted that search subscriptions and sites that republish other feeds could cause duplicates, as could publishers offering the same feed in both RSS and Atom formats.

Why feed readers show false duplicate posts

• Changing feed content: related posts, ads, dates or counters added automatically to each feed item.
• Changed post IDs: if the unique ID (the RSS guid element (external site)) of a post changes, readers see it as a new item. This can happen after a site migration or a domain or protocol change.
• Multiple feed formats: subscribing to both an RSS and an Atom feed of the same site shows every post twice.
• Republished content: aggregator feeds and scrapers repost the same article.
• Edits to old posts: genuinely updating an old post can move it back to the top, depending on the reader.

How to fix duplicate RSS posts as a blogger

1. Remove automatic extras from your feed. Related-post lists, share counts and rotating ads change often. I kept related posts in my feed at the time because they helped readers, but removing them is the surest fix.
2. Keep post GUIDs stable. WordPress sets each post’s GUID when it is first published. Do not rewrite GUIDs in the database when you move a site.
3. Offer one main feed. Link to a single feed URL so readers do not subscribe to duplicates.
4. Limit items in the feed. The more posts your feed contains, the more older items can change. A feed of 10 to 20 recent posts rarely has this issue.
5. Check your caching. A caching plugin can also affect when feeds update; see how caching can delay RSS feed updates.

How to fix duplicate posts in RSS feed readers as a reader

• Check that you are not subscribed to both the RSS and Atom feeds of the same site.
• Look in your reader’s settings for options about updated articles.
• Try a different reader if one is too sensitive. Back in 2006 I switched from Bloglines to Google Reader. Today see our list of the best RSS readers.

FAQ

Why does an old blog post show as new in my RSS reader?

Usually because the feed item changed slightly or its unique ID changed, so the reader treats it as updated or new.

Do related posts in feeds cause duplicates?

They can. When a new post is added to the related lists of older posts, those older feed items change.

Does changing my domain or moving to HTTPS create duplicates?

It can if the post IDs in your feed change. Keep the original GUIDs when you migrate.

Should I offer both RSS and Atom feeds?

It is fine to have both, but promote one main feed so readers do not subscribe twice.