You just change DESC to ASC in the code

I have used "Remove duplicate node code". Its working for small data but i have more than 6lac nodes and when i used this on that its not working. please help me if you have any solution.

Thanks in advance

Came across this post and needed a D7 version also, so I spent some time converting it. I have done basic testing, but you're encouraged to do testing of your own! :)

Some things could be improved, but it works. I did change the form a bit so you can select what content types you want to dedupe, which is handy if you want to avoid deleting everything at once because of memory constraints.

The SQL logic is almost the same, except if the node created times are the same, the highest nid will survive the delete.

/**
* @file
* Remove Duplicate Nodes.
*/

/**
* Implementation of hook_menu().
*/
function nodededupe_menu() {
    $items['admin/content/dedupe'] = array(
        'title' => 'Dedupe',
        'description' => 'Delete Duplicate Nodes',
        'page callback' => 'drupal_get_form',
        'page arguments' => array('nodededupe_content_command'),
        'access arguments' => array('administer site configuration'),
        'type' => MENU_NORMAL_ITEM,
        'file' => NULL,
    );
    return $items;
}
/**
* Build Form
*/
function nodededupe_content_command() {
    $options = array();
    $types = node_type_get_types();
    foreach ($types as $type) {
      $options[$type->type] = $type->name;
    }
    $form['nodededupe_node_types'] = array(
        '#type' => 'checkboxes',
        '#title' => t('You can select content type from which duplicates are removed.'),
        '#options' => $options,
        //'#default_value' => variable_get('nodededupe_node_types', array('page')),
        '#description' => t('Duplicate content from the selected content types will be deleted.'),
    );
    $form['submit'] = array(
        '#type' => 'submit',
        '#value' => t('Dedupe'),
    );
    return $form;
}
/**
* Call delete function and set message.
*/
function nodededupe_content_command_submit($form, $form_state) {
    $types_del = array();
    $types = $form_state['values']['nodededupe_node_types'];
    foreach ($types as $idx => $type) {
      if ($type === 0) {
        continue;
      }
      $types_del[] = $type;
    }

    $nodededupe_m = 'Duplicates deleted from content types: '. implode(", ",$types_del);
    nodededupe_delete($types_del);
    drupal_set_message(check_plain($nodededupe_m));
}
/**
* Delete duplicates from selected content type, based on title. By Robert Douglass.
* @see <a href="http://robshouse.net/blog-post/remove-duplicate-nodes-dedupe-based-title
" title="http://robshouse.net/blog-post/remove-duplicate-nodes-dedupe-based-title
" rel="nofollow">http://robshouse.net/blog-post/remove-duplicate-nodes-dedupe-based-title
</a> */
function nodededupe_delete($types_del) {
    $prevobj = array();
    $result = db_query("SELECT n.nid, n.title, n.created FROM node n
    	inner join
      	(SELECT title FROM node
        	WHERE type in (:types)
        	GROUP BY title HAVING count(*) > 1) n2
     	on n.title = n2.title
    ORDER BY title, created, nid DESC", array(':types' => $types_del));
    
    foreach ($result as $obj) {
        if ($obj->title == $prevobj->title) {
            node_delete((int)$obj->nid);
            drupal_set_message("Deleted node nid={$obj->nid}, title={$obj->title}, created={$obj->created}");
        }
        $prevobj = $obj;
    }
}

... and here is the .info file I was using:

name = Dedupe
description = "Node dedupe module taken from http://drupal.org/node/720190"
core = 7.x
package = Custom

files[] = nodededupe.module

Create a hook and call the delete function followed by the content-types arrays as an argument

function yourmodulename_cron() {
nodededupe_delete('content-type');
}

Something like that.