(3)Where a sentence has been awarded by a court in respect of offences in several charges and has been confirmed, and anyone of such charges or the finding thereon is found to be invalid, the authority having power to mitigate, remit or commute the punishment awarded by the sentence shall take into consideration the fact of such invalidity, and if it seems just, mitigate, remit or commute the punishment awarded as it seems just, having regard to the offences in the charges which with the findings thereon are not invalid, and the punishment as so modified shall be as valid as if it had been originally awarded only in respect of those offences.
