How about--

If a print is lost in the mail, it's the sender's option whether to send a replacement print.

If the print was actually sent, it just the luck of the draw for the recipient, but if the print was never sent--it's doubtful that a "second" print would be sent. So if a good faith effort was made by the sender, it should be up to that photographer to make the decision--based on availability/amount of work/postage.