Getting duplicate page titles when making changes to a page

Check your template's code

This is a known behavior caused by template coding. Some templates want to add your website's title to all of the pages, and since Joomla! does not do that automatically, they've added a little hack. In your template's index.php file there should be a line similar to this one:

By removing (or commenting - just add two slashes in front of it //) the above line you shouldn't run into this problem any more. Update your page titles through the RSSeo! Pages menu and you will no longer get duplicate titles. Unfortunately, this operation has to be done for all pages that have already been crawled.

Check your Artio JoomSEF settings

If you are using Artio JoomSEF, go to Extensions > Plugin Manager and edit the System - ARTIO JoomSEF plugin. Under "Plugin Parameters", make sure "Use sitename in page titles" is set to "No".

The reason why you need to do this is simple: when you edit your page title with RSSeo!, the information is saved in the database and whenever that particular page is accessed, the RSSeo! System Plugin detects it and adds the new, edited title to it. After this, the Artio JoomSEF System Plugin comes along and adds the site title to the already edited title and thus duplicating it.

Check your sh404SEF settings

If you are using sh404SEF, go to Components > sh404SEF and click on "sh404SEF Configuration". Under the "Meta/SEO" tab there are two options: "Insert before page title" and "Append to page title". Make sure these are empty. The same explanation for Artio JoomSEF is valid for sh404SEF.

Check if you are using the Title Manager plugin

If you are using the Title Manager System Plugin, you need to either go to Extensions > Plugin Manager and edit the System - Title Manager plugin and disabled it or completely uninstall it.