R. Akiva: It was taught in the Beraisos of Kesuvos (marriage documents) of the Yeshiva of Levi - If a person said that he lost his document, Beis Din check if his words are accurate, such as by bringing its witnesses to testify that they signed, and the Beis Din then write for him a new document.

Beraisa (Rabban Shimon ben Gamliel): Even for selection documents (where there is no financial loss without it), they (go to the trouble of) validating it.