node distinct is not being enforced

I have a simple table view listing all content of type 'noticeboard', that is published, and distinct. However, it is showing duplicates in the list.

Here's what the export looks like:

  $view = new stdClass();
  $view->name = 'view_vs_noticeboard';
  $view->description = '';
  $view->access = array (
);
  $view->view_args_php = '';
  $view->page = TRUE;
  $view->page_title = '';
  $view->page_header = '';
  $view->page_header_format = '1';
  $view->page_footer = '';
  $view->page_footer_format = '1';
  $view->page_empty = '';
  $view->page_empty_format = '1';
  $view->page_type = 'teaser';
  $view->url = 'vs-noticeboard';
  $view->use_pager = TRUE;
  $view->nodes_per_page = '10';
  $view->block = TRUE;
  $view->block_title = '';
  $view->block_header = '';
  $view->block_header_format = '1';
  $view->block_footer = '';
  $view->block_footer_format = '1';
  $view->block_empty = '';
  $view->block_empty_format = '1';
  $view->block_type = 'table';
  $view->nodes_per_block = '5';
  $view->block_more = TRUE;
  $view->block_use_page_header = FALSE;
  $view->block_use_page_footer = FALSE;
  $view->block_use_page_empty = FALSE;
  $view->sort = array (
    array (
      'tablename' => 'comments',
      'field' => 'timestamp',
      'sortorder' => 'ASC',
      'options' => 'normal',
    ),
  );
  $view->argument = array (
  );
  $view->field = array (
    array (
      'tablename' => 'users',
      'field' => 'uid',
      'label' => '',
    ),
    array (
      'tablename' => 'node',
      'field' => 'title',
      'label' => 'Title',
      'handler' => 'views_handler_field_nodelink',
      'options' => 'link',
    ),
    array (
      'tablename' => 'node_comment_statistics',
      'field' => 'comment_count',
      'label' => 'Replies',
      'handler' => 'views_handler_comments_with_new',
    ),
    array (
      'tablename' => 'node',
      'field' => 'created',
      'label' => 'Posted',
      'handler' => 'views_handler_field_date_small',
    ),
  );
  $view->filter = array (
    array (
      'tablename' => 'node',
      'field' => 'status',
      'operator' => '=',
      'options' => '',
      'value' => '1',
    ),
    array (
      'tablename' => 'node',
      'field' => 'type',
      'operator' => 'OR',
      'options' => '',
      'value' => array (
  0 => 'noticeboard',
),
    ),
    array (
      'tablename' => 'node',
      'field' => 'distinct',
      'operator' => '=',
      'options' => '',
      'value' => array (
  0 => 'distinct',
),
    ),
  );
  $view->exposed_filter = array (
  );
  $view->requires = array(comments, users, node, node_comment_statistics);
  $views[$view->name] = $view;