Nothing in subchapter I of this chapter shall be deemed to reduce the relief or retirement compensation to which any person is entitled on the effective date of such sections and the rights of such persons and their survivors shall continue in the same manner and to the same extent as if such sections had not been enacted.

There are hereby authorized to be appropriated from revenues of the United States such sums as are necessary to reimburse the District of Columbia, on a monthly basis, for benefit payments made from revenues of the District of Columbia to or for federal employees and to or for the surviving children and spouse of such federal employees under the provisions of subchapter I of this chapter, to the extent that such benefit payments exceed the deductions from the salaries of federal employees for credit to the revenues of the District of Columbia, and for the administrative costs associated with making such benefit payments. For the purpose of this section:

Notwithstanding any other provision of law, no person entitled to receive any benefit under subchapter I of this chapter on account of death incurred, an injury received, or disease contracted, or an injury or disease aggravated, in the performance of duty shall be entitled, because of the same death, injury, disease, or aggravation, to benefits under subchapter I of Chapter 81 of Title 5, United States Code.