code: public function hasOtherNodeWithSameParentAndOrder($parentId, $order, $nodeId, $siteId)
      {
          $qa = $this->createAggregationQueryBuilderWithSiteId($siteId);
          $qa->match(
              array(
                  'parentId' => $parentId,
                  'order'    => $order,
                  'nodeId'   => array('$ne' => $nodeId),
                  'deleted'  => false,
                  'nodeType' => NodeInterface::TYPE_DEFAULT
              )
          );
          $node = $this->singleHydrateAggregateQuery($qa);
  
          return $node instanceof NodeInterface;
      }
docs: @param string $parentId
  @param int    $order
  @param string $nodeId
  @param string $siteId
  
  @return bool