Polylang Support

Hi! ??

You have added WPML support. If you wanted to add Polylang support, you could use the following code:

function duplicate_post_polylang_init() {
	if ( function_exists( 'pll_get_post_translations' ) ) {
		add_action( 'dp_duplicate_page', 'duplicate_post_polylang_copy_translations', 10, 3 );
		add_action( 'dp_duplicate_post', 'duplicate_post_polylang_copy_translations', 10, 3 );
	}
}
add_action( 'admin_init', 'duplicate_post_polylang_init' );

/**
 * Add support for duplicate posts for Polylang. Duplicate all languages together.
 *
 * @param int     $new_post_id   Post ID of new cloned post.
 * @param WP_Post $original_post WP_Post object of the original post.
 * @param string  $status        Post status of new cloned post.
 */
function duplicate_post_polylang_copy_translations( $new_post_id, $original_post, $status = '' ) {
	remove_action( 'dp_duplicate_page', 'duplicate_post_polylang_copy_translations', 10 );
	remove_action( 'dp_duplicate_post', 'duplicate_post_polylang_copy_translations', 10 );

	$languages = pll_get_post_translations( $original_post->ID );
	$post_ids  = [];
	foreach ( $languages as $slug => $post_id ) {
		// Do not duplicate post again.
		if ( $original_post->ID === $post_id ) {
			$post_ids[ $slug ] = $new_post_id;
			continue;
		}
		$post_ids[ $slug ] = duplicate_post_create_duplicate( get_post( $post_id ), $status );
	}
	pll_save_post_translations( $post_ids );
}