WP SMUSH PRO

"Fatal error: Cannot redeclare get_plugin_dir() (previously declared in /var/www/vhosts/studio-todo.com/httpdocs/wp-content/plugins/wp-smushit/wp-smush.php:118) in /var/www/vhosts/studio-todo.com/httpdocs/wp-content/plugins/wp-smush-pro/wp-smush.php on line 116"

i can't install this plug in. this is the error script. can you help me?