CIBlockElement::GetRealElement

                foreach ($offers_data[$model_id] as $id=>$offer) {
                    $ELEMENT_ID = \CIBlockElement::GetRealElement($id);
                    $arDiscounts = \CCatalogDiscount::GetDiscountByProduct(
                        $ELEMENT_ID,
                        array(1,2,3),
                        "N",
                        1,
                        "s1"
                    );

                    if ($arDiscounts[0]) {
                        $mas_id[] = $ELEMENT_ID;
                        \CIBlockElement::SetPropertyValues($ELEMENT_ID,
                            OFFERS_IBLOCK_ID,
                            "Y",
                            "LABEL_SPEC_PRICE");
                    } elseif (!$arDiscounts[0] && $offer["PROPERTIES"]["LABEL_SPEC_PRICE"]["VALUE"] == "Y") {
                        \CIBlockElement::SetPropertyValues($ELEMENT_ID,
                            OFFERS_IBLOCK_ID,
                            "N",
                            "LABEL_SPEC_PRICE");
                    }
                    $arDiscounts = "";
                }