Answer by andrewsi for Wordpress Double Title In header - No seo plugins

You've got two calls that look like they're duplicated. Inside the PHP block in the <title> tag, you're calling:

wp_title( '|', true, 'right' );

Accord to the documentation, this will return the title of the post.

Then, after your PHP block, you're calling:

echo get_the_title($ID)

Which does exactly the same thing.