I can not activate WP SMUSH PRO

Plugin could not be activated because it triggered a fatal error.
Fatal error: Cannot redeclare i18n() (previously declared in /home2/lobalfam/public_html/wp-content/plugins/wp-smushit/wp-smush.php:278) in /home2/lobalfam/public_html/wp-content/plugins/wp-smush-pro/wp-smush.php on line 276