Double bar “|” in title (By WP SEO Yoast?)

Question

I am wondering why my pages (post doesn't have this problem) have a double bar "|" in them

eg. About || Jiew Meng's Blog

UPDATE

Actually it appears in other pages too, like this. In this case, its a custom post type. Note the repeated site name

KLIF Media v2 |  | Jiew Meng's BlogJiew Meng's Blog

UPDATE 2 (@CorvanNoorloos)

Ok, I changed my title to

wp_title('')

Instead of the default wp_title('|', true, 'right') in TwentyTen. It fixed the double bar problem, but

If I go a Custom Post Type archive link, I get something like

PortfolioJiew Meng's Blog

If I go a custom post type single page link, I get

KLIF Media v2 - Jiew Men's BlogJiew Meng's Blog

If I force rewrite titles, it mostly works except for some pages, becoming

- Jiew Meng's Blog

I think I need to manually set the page title if I used this option?

Answer 1

I use this plugin together with TwentyTen too and encountered the same problem.

My solution is to leave wp_title( '|', true, 'right' ); unchanged but only enable the call to function bloginfo() in the next line if plugin WordPress SEO is inactive.

include_once( ABSPATH . 'wp-admin/includes/plugin.php' );

// Add the blog name.
if ( is_plugin_inactive('wordpress-seo/wp-seo.php') ) {
    bloginfo( 'name' );  //this call conflicts with plugin "Wordpress SEO"
}

I don't use 'Force rewrite titles'. For the title templates I use %%title%% | %%sitename%%. For the homepage I've entered my custom title text.

Answer 2

It's probably caused by a theme you've installed (in this case a somewhat modified version of TwentyEleven).

Joost's plugin needs <?php wp_title(''); ?> in the header.php.

Have you tried to enable “Force rewrite titles”? (which is currently available at SEO -> Titles)