Piggul and nossar do not combine with each other, because they are two [distinct] names. A sheretz and neveilah, as well as neveilah and flesh of a [human] corpse, do not combine with each other to transmit tumah even like the more-lenient [aspect] of the two. Food that contracted tumah from an av hatumah and [food] that contracted tumah from a vlad hatumah combine with each other to transmit tumah like the more-lenient [aspect] of the two.