Whenever any record or document is copied or reproduced by microphotographic, microfilm, or other mechanical process as provided in this section, it shall be made in duplicate, and the custodian thereof shall place one copy in a fireproof vault or fireproof storage place, and he shall retain the other copy in his office with suitable equipment for displaying such record by projection to not less than its original size or for preparing, for persons entitled thereto, copies of the record.