What is the validity of hiring transport for two loads (one known, one unknown) for a single, fixed price?

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If both parties know the second load, the contract is valid for both. If they are both unknown, the contract is void entirely because it is a single contract with a single price for both a known and an unknown object. This differs from the preceding case. If the second load is known but usurped, or if a legal impediment prevents contracting for it, the contract for that load is void, and there are two opinions regarding the validity of the contract for the first load, depending on the principle of severability of the transaction. Validity of the first load is favored if their measures are known or one is proportionally known to the other, as the share of the hire is known; otherwise, invalidity is favored due to uncertainty of the consideration.