Trying to activate WP Smush It Pro, fatal error...

Fatal error: Cannot redeclare i18n() (previously declared in /ohiomobilegaming-clone/wp-content/plugins/wp-smushit/wp-smush.php:278) in /ohiomobilegaming-clone/wp-content/plugins/wp-smush-pro/wp-smush.php on line 274

Can't activate the plugin...

advice?