Bava Batra 164 - Dating a Bound Document
Rabbi Chanina ben Gamliel said that although in a bound document the witnesses should sign on the outside , nevertheless if they signed on the inside, it is valid, since one can unbind it and convert it to a regular document.
Rebbi offered a rebuttal: the dating system on the two types of document is different. Jews dated their documents by the year of rule of the current monarch. Governments used to add a year to the number of years of the current king, to proclaim that a relatively new monarch is already established. The Sages, desiring to make a bound document very complex, also added a year for bound documents, but not for regular ones. One could unbind the document, effectively changing the loan date, receive the payment, pretend to have lost the loan document, offer a receipt, and then collect the second time.
But according to Rabbi Chanina, a receipt is never used.
Art: Collier, Edwart - Self-Portrait with a Vanitas Still- Life