/**
  * Check if two order items are the same
  * @param Object - $orderItem should be a ProductVariation_OrderItem;
  * @return Boolean
  **/
 function hasSameContent($orderItem)
 {
     $parentIsTheSame = parent::hasSameContent($orderItem);
     return $parentIsTheSame && $orderItem instanceof ProductVariation_OrderItem;
 }
 function hasSameContent($orderItem)
 {
     $equals = parent::hasSameContent($orderItem);
     return $equals && $orderItem instanceof ProductVariation_OrderItem && $this->_productVariationID == $orderItem->_productVariationID && $this->_productVariationVersion == $orderItem->_productVariationVersion;
 }