Section 9. Returns to the commissioner under section twenty-two A of chapter one hundred and seventy-two, records of examinations of banks made under section two of this chapter, certificates or other form of acknowledgment filed with the commissioner under section three of this chapter, reports made under section twenty-six of chapter one hundred and sixty-eight, and reports made under section eighteen of chapter one hundred and seventy, may, after six years from the date of their receipt, be destroyed or disposed of by order of their lawful custodian with the approval of the commissioner, and any proceeds received in the course of their disposal shall be paid to the commonwealth; provided, however, that if the commissioner shall have received actual notice, in writing, of any pending judicial proceeding in which such returns, records, certificates or other form of acknowledgment or reports are to be offered as evidence thereat, such returns, records, certificates, or other form of acknowledgment or reports shall not be destroyed or disposed of until after the final determination of such judicial proceeding.