How to remove duplicate blog title

I normally use WP SEO by Yoast, but here’s a troubleshoot:

• what if you use only wp_title(''); ^{(this is a WPSEO requirement)}
• what do you have as Home Title at the plugin’s settings page?
  
• search your theme’s functions.php for a similar hook, and disable if found:
  add_filter( 'wp_title', 'twentyten_filter_wp_title', 10, 2 );
• dig into WordPress forums for similar issues: http://wordpress.org/search/all-in-one-seo-pack+wp_title?forums=1