Thanks for all! it works properly ^^
I change a little thing using an array to list easily several post_type.
$hide_for_posttype = array('post_type_A','post_type_B','post_type_C');
if( (in_array($post->post_type, $hide_for_posttype)) && isset($actions['duplicate_post']) ) {
unset( $actions['duplicate_post'] );
}
