Is the holder of a Mukataba (contract of manumission for a fixed payment) obligated to accept a different commodity than the one specified in the contract?

Primary text

If a contract of manumission (Mukataba) is stipulated for a specific type of currency or commodity, the obligated party is not required to accept anything other than that exact type. For instance, if the contract is for Dinars (gold coins), accepting Dirhams (silver coins) or other goods is not obligatory. Similarly, if the contract specifies Dirhams, accepting Dinars or other goods is not required. If the contract is for a described commodity, accepting anything else is not mandatory.