Copies from the records, books, and accounts of a savings bank and its holding company shall be competent evidence in all cases, equal with originals thereof, if there is annexed to such copies an affidavit taken before a notary public or clerk of a court under seal, stating that the affiant is the officer of the savings bank or holding company having charge of the original records, and that the copy is true and correct and is full so far as the same relates to the subject matter therein mentioned.