Edit permalink for old posts and not show on top of RSS feed

by

It seems the reason for this is guid tag in RSS, which contains links
I have changed

If you’ve changed the GUID in the database…

From the Codex:

When doing the above and changing the URLs directly in the database,
you will come across instances of the URL being located in the “guid”
column in the wp_posts tables.

It is critical that you do NOT change the contents of this field.

The term “GUID” stands for “Globally Unique Identifier”. It is a field
that is intended to hold an identifier for the post which a) is unique
across the whole of space and time and b) never, ever changes. The
GUID field is primarily used to create the WordPress feeds.

…

Thus, changing the GUID will mean that many feedreaders will suddenly
display your content in the user’s reader again as if it was new
content, possibly annoying your users.

…

Never, ever, change the contents of the GUID column, under any circumstances.

… then you’ve broken the mechanism used to prevent this kind of feed “re-publishing”.

Unless you have a backup of the database, this may not be fixable. You will need to find all the posts which have had their guids changed and put that guid back to exactly what it was before.

Another possibility is that you are constructing the feed incorrectly and are creating this:

<guid isPermaLink="false">
http://host1.com/blog1/slug-of-article
</guid>

… using the post permalink instead of the guid. That should be more easily fixable.