Why does a feed item sometimes appear twice?
Duplicate-looking items are often caused by small changes in feed data rather than by an obvious reader error.
about 2 min read
Feeds need stable identifiers
Feed readers identify entries through values such as link, ID or publication date. If a website changes these values, an old post can look like a new item.
This can happen after redesigns, imports, corrections or plugin changes.
Caches can also confuse things
Some servers briefly deliver different versions of the same feed. A reader then sees old and new data alternating.
After a while this often settles by itself.
Why readers need to be careful
A feed reader cannot simply compare headlines. Two different posts can have the same or very similar titles.
That is why readers use technical signals such as guid, link and date. If those signals are unstable, showing a duplicate is often safer than accidentally hiding a genuinely new post.
Do not panic immediately
A single duplicate is usually not a serious problem. If duplicates keep appearing, it is worth checking the original feed and its technical fields.
For the bigger picture, see what happens when you open a feed.