Under regulations prescribed by the Secretary of the Senate, a person serving as a Senator or officer or employee whose compensation is disbursed by the Secretary of the Senate may designate a beneficiary or beneficiaries to be paid any unpaid balance of salary or other sums due such person at the time of his death. When any person dies while so serving, any such unpaid balance shall be paid by the disbursing officer of the Senate to the designated beneficiary or beneficiaries. If no designation has been made, such unpaid balance shall be paid to the widow or widower of that person, or if there is no widow or widower, to the next of kin or heirs at law of that person.Section 50 of the Revised Statutes shall not be effective as to persons included within the foregoing.