Fotis introduced in the K2 2.6.4 news these following options:

"Default parent menu for user pages (optional)"
"Default parent menu for tag listings (optional)"

These options kill the duplicated URL issue with tags and user pages. But for some reason, he removed these options in K2 2.6.5, which means you have yet again duplicated URLs with tags and author pages. The new SEF advance options can't do nothing about this.

At this point, there hasn't been a news to K2 2.6.5 posted, so lets hope that Fotis can explain his decision to remove these options soon.

In the meantime, simply don't update to K2 2.6.5.

Are they back in 2.6.6 ?

There is no K2 2.6.6. The latest version is 2.6.5.

they was deleted only from config.xml
variables are still in the plugins/system/k2.php

You can put these back in the config.xml, but they won't work anymore. I checked this.

did you uncomment this line:
//define('K2_USERS_ITEMID', $componentParams->get('defaultUsersItemid'));
in plugins/system/k2.php?

No I didn't, but thanks for the heads-up.

// Define the default Itemid for users and tags. Defined here instead of the K2HelperRoute for performance reasons.
// UPDATE : Removed in K2 2.6.5. All K2 links without Itemid now use the anyK2Link defined in the router helper.
//define('K2_USERS_ITEMID', $componentParams->get('defaultUsersItemid'))
//define('K2_TAGS_ITEMID', $componentParams->get('defaultTagsItemid'));

So that explains it then. I will do some testing now and report my results shortly.

As I thought, you still have duplicated URLs with tag and user pages when those lines in the k2.php are commented.

Removed in K2 2.6.5. All K2 links without Itemid now use the anyK2Link defined in the router helper.

The advanced SEF options ain't do nothing about this. I don't know what this "anyK2Link" is supposed to mean, but it obviously isn't working. Tags and user pages links all start with "component/k2" if not assigned to a menu, resulting in multiple duplicated URLs accross your site.

comment them out and write a new issue about anyK2Link: duplicated urls are back :(:(:( :angry: :angry: :angry: Its in route.php