With WP 3.7.1 I get this HTML code on my installation:
<meta charset="UTF-8"> <title>Luigi Ros</title> <link rel="profile" href="http://gmpg.org/xfn/11"> <link rel="pingback" href="http://luigirosa.com/xmlrpc.php"> <meta charset="UTF-8" /> <title>Luigi Rosa</title>
The first <title> is in the line 5 of header.php (note that for unknown reasons the last character is missing):
<title><?php wp_title(); ?></title>
The second (correct) <title> come from line 9:
<?php wp_head(); ?>
Since wp_head() already sends <title> I think that the <title> in line 5 of header.php could be deleted.