<p>When reading my RSS feed with the Thunderbird feed reader, some entries are duplicated. <a href="https://en.wikipedia.org/wiki/Google_Reader" rel="nofollow noreferrer">Google Reader</a> does not have the same problem.</p>
<p>Here is the faulty feed:
<a href="http://plcoder.net/rss.php?rss=Blog" rel="nofollow noreferrer">http://plcoder.net/rss.php?rss=Blog</a></p>
<p>There is a problem, but where?</p>
<p>I added a <a href="https://en.wikipedia.org/wiki/Globally_unique_identifier" rel="nofollow noreferrer">GUID</a>, but the problem remains. Other feeds do not duplicate like mine, so I will do rework on this module and replace this old good code.</p>
<p>Conclusion: I completely reworked the RSS generator code, and it's OK. I think I was using a very old version of <a href="https://en.wikipedia.org/wiki/Resource_Description_Framework" rel="nofollow noreferrer">RDF</a>.</p>

Try adding a
```
<guid>
```
tag to each item, giving it a permalink.  i.e.:
```
```
<item rdf:about="http://plcoder.net/?doc=2134&amp;amp;titre=mon-pc-se-la-pete">
  <link>http://plcoder.net/?doc=2134&amp;amp;titre=mon-pc-se-la-pete</link>
  <guid>http://plcoder.net/?doc=2134&amp;amp;titre=mon-pc-se-la-pete</guid>
  ...
</item>
```
```
Without a GUID, if any of the content in the post changes, your RSS aggregator might think that it is a new post.  With the GUID, even if the content of that item changes, your RSS aggregator
should
just update the post, instead of treating it as a new item.