protected function _getQuoteItemQtyForCheck($productId, $quoteItemId, $itemQty)
 {
     if (!Mage::helper('udmulti')->isActive()) {
         return parent::_getQuoteItemQtyForCheck($productId, $quoteItemId, $itemQty);
     }
     $qty = $itemQty;
     $pidKey = $this->getUdropshipVendor() ? $this->getUdropshipVendor() . '-' . $productId : $productId;
     if (isset($this->_checkedQuoteItems[$pidKey]['qty']) && !in_array($quoteItemId, $this->_checkedQuoteItems[$pidKey]['items'])) {
         $qty += $this->_checkedQuoteItems[$pidKey]['qty'];
     }
     $this->_checkedQuoteItems[$pidKey]['qty'] = $qty;
     $this->_checkedQuoteItems[$pidKey]['items'][] = $quoteItemId;
     return $qty;
 }