Cannot redeclare class sef_tag

When I try to access Joomla Tags (with SEF Advance enabled), I get this error:

Fatal error: Cannot redeclare class sef_tag in F:\Program Files\EasyPHP1-8\www\components\com_tag\sef_ext.php on line 14

Is this a problem with SEF Advance, Joomla Tags or how my localhost server is set up ??? Thanks!

SEF Advance doesn't contain a class by that name, so it must be an issue caused by Tags component or its SEF extension.

Hi Saka,

Strangely enough with the upgrade to 5.5.1 the error message as per 1st post has disappeared, but none of the tagged content is showing up correctly on localhost.

I made a post on Phil's forum about it: forum.phil-taylor.com/viewtopic.php?f=16&t=2057