_wp_copy_post_meta

WordPress Version: 6.4

/**
 * Copy post meta for the given key from one post to another.
 *
 * @since 6.4.0
 *
 * @param int    $source_post_id Post ID to copy meta value(s) from.
 * @param int    $target_post_id Post ID to copy meta value(s) to.
 * @param string $meta_key       Meta key to copy.
 */
function _wp_copy_post_meta($source_post_id, $target_post_id, $meta_key)
{
    foreach (get_post_meta($source_post_id, $meta_key) as $meta_value) {
        /**
         * We use add_metadata() function vs add_post_meta() here
         * to allow for a revision post target OR regular post.
         */
        add_metadata('post', $target_post_id, $meta_key, wp_slash($meta_value));
    }
}