Section 42. Whenever a city or town causes an audit of its accounts or the accounts of separate departments to be made by a person of its own selection, the city or town clerk shall immediately, upon the employment of such person, file his name and address with the director, and such person shall, within ten days after making the report of his audit and recommendations to the city or town, file a certified copy thereof with the director; and in any such case the director may, in his discretion, accept the audit so made, or cause an audit to be made under section forty.