Twenty Eleven Theme - SEO Yoast duplicate site titles

I'm using a Twenty Eleven Theme with the SEO Yoast Plugin and I have encountered that once the plugin is installed, duplicate site titles appear on my site, like this:

titleHome | beethetravelerbeethetraveler | a life journey/title

I googled and found a fix with editing the header.php and replace everything in between the title…/title with the following.

title?php wp_title(''); ?/title

My header.php looks like the following: wp_title( '|', true, 'right' );

So I'm not sure how to do it. Can somebody point me in the right direction? Really appreciate it :)