Any contractual entitlement to firm power which is based on electric power acquired from, or on behalf of, a customer pursuant to
section 839d of this title shall be in addition to any other contractual entitlement to firm power not subject to restriction that such customer may have under this section. For the purposes of this subsection, references to amounts of power acquired by the Administrator pursuant to
section 839d of this title shall be deemed to mean the amounts specified in the resource acquisition contracts exclusive of any amounts recognized in such contracts as replacement for Federal base system resources.