"Comment: duplicate ..." in watchdog, even when editing a comment?

I guess this message is written to note a user entered a duplicated message. Not sure how much sense there is, but maybe there is little sense when one just changes the status, the user or the date of the message?

What if this message was not written when the user has 'administer comments' permission and it is editing a comment. ie. write the message when creating, but not when editing (even if the text is being changed, let's suppose the admin knows what (s)he is doing...).

This is the code snippet, located in comment_save():

      // Check for duplicate comments.  Note that we have to use the
      // validated/filtered data to perform such check.
      $duplicate = db_result(db_query("SELECT COUNT(cid) FROM {comments} WHERE pid = %d AND nid = %d AND subject = '%s' AND comment = '%s'", $edit['pid'], $edit['nid'], $edit['subject'], $edit['comment']), 0);
      if ($duplicate != 0) {
        watchdog('content', t('Comment: duplicate %subject.', array('%subject' => theme('placeholder', $edit['subject']))), WATCHDOG_WARNING);
      }

Does anyone know what "Note that we have to use the validated/filtered data to perform such check." means?

Also, note that comment duplicates are checked only against the same node and comment parent. That makes me think it is to prevent users from posting the same comment twice. If so, what we have here is pretty useless. The message is sent only to watchdog, so...

I'm wondering if it would be better to remove that check?