What does `drupal_clone($node)` do in Drupal? Will it clone a node?  I know the node will be saved only if `node_save($clone)` is rendered. So what will happen when `drupal_clone($node)` is rendered ?

    /**
     * Generate a node preview.
     */
    function node_preview($node) {
        if (node_access('create', $node) || node_access('update', $node)) {
            // Load the user's name when needed.
            if (isset($node->name)) {
                // The use of isset() is mandatory in the context of user IDs, because
                // user ID 0 denotes the anonymous user.
                if ($user = user_load(array('name' => $node->name))) {
                    $node->uid = $user->uid;
                    $node->picture = $user->picture;
                } else {
                    $node->uid = 0; // anonymous user
                }
            } else if ($node->uid) {
                $user = user_load(array('uid' => $node->uid));
                $node->name = $user->name;
                $node->picture = $user->picture;
            }
    
            $node->changed = time();
    
            // Extract a teaser, if it hasn't been set (e.g. by a module-provided
            // 'teaser' form item).
            if (!isset($node->teaser)) {
                $node->teaser = empty($node->body) ? '' : node_teaser($node->body, $node->format);
                // Chop off the teaser from the body if needed.
                if (!$node->teaser_include && $node->teaser == substr($node->body, 0, strlen($node->teaser))) {
                    $node->body = substr($node->body, strlen($node->teaser));
                }
            }
    
            // Display a preview of the node.
            // Previewing alters $node so it needs to be cloned.
            if (!form_get_errors()) {
                $cloned_node = drupal_clone($node);
                $cloned_node->build_mode = NODE_BUILD_PREVIEW;
                $output = theme('node_preview', $cloned_node);
            }
            drupal_set_title(t('Preview'));
    
            return $output;
        }
    }

**Real Issue**
=============

I am getting the node cloned when clicking the preview button. Is it related to any code changes?