Hello Arne,
you are right. None of the plugins is responsible for the duplicate feed titles.
It is your theme Graphene.
The file /wp-content/themes/graphene/includes/theme-head.php includes a function which gets applied to the filter hook wp_title (see the laast line in that file add_filter( 'wp_title', 'graphene_title', 10, 3 ); ).
The wp_title hook filter can be used to influence not all kind of titles like the title of a page. WordPress functions like get_wp_title_rss and wp_title_rss which create the title of the RSS and ATOM feeds use also the function wp_title which contains the hook with the same name. That is why the function graphene_title influences the feed titles too.
In line 458 of the theme-head.php you can find the » which makes the feeds invalid. The problem is that such character entity references are almost not allowed in XML. besides 5 exception it is necessary to use the numerical entity reference (see http://en.wikipedia.org/wiki/Html_entities#XML_character_references). In this case it would be correct to use ». But the that will not change the doubled feed titles.
Modifying the titles via Graphene Theme Options > Display > Miscellaneous Display Options seems also not helpful if it comes to the doubled titles.
I guess since the modifications of the feed titles does not seem intentional, it would be okay to modify the section from line 452 to 459 in the file theme-head.php like this:
if ( is_feed() ) {
$title = $default_title;
} else {
if ( $graphene_settings['custom_site_title_content'] ) {
$title = $graphene_settings['custom_site_title_content'];
$title = str_replace( '#site-name', get_bloginfo( 'name' ), $title );
$title = str_replace( '#site-desc', get_bloginfo( 'description' ), $title );
$title = str_replace( '#post-title', $default_title, $title );
} else {
$title = $default_title . " » " . get_bloginfo( 'name' );
}
}
This will prevent the theme from modifying the title if a certain title is in a feed.
codenaga
