What is the ruling if two parties exchange currency (like Dinars) by weight estimate, separate, and one finds a deficiency in what they received?

Primary text

If two parties trade currency (like Dinars for Dinars) based on an estimate, and upon separation, one finds the received amount deficient, the exchange is voided. This is because the transaction constitutes an unequal exchange of the same metal (gold for gold with excess/deficiency).