Notwithstanding any provision of this Act [this chapter], the aggregate (gross) rate of compensation of any employee immediately prior to the effective date of this Act [Jan. 1, 1965] shall not be reduced by reason of the enactment of this Act.
“(b) For the purposes of applicable law relating to the payment to any individual of compensation from more than one civilian office or position, each employee of the House to whom this Act applies who, immediately prior to the effective date of this Act—
is receiving basic compensation from more than one civilian office or position and
is in compliance with such law
shall be held and considered to be in compliance with such law on and after such effective date, notwithstanding the enactment of this Act, so long as such employee continues to receive, without break in service of more than thirty days, the same or lower rate of basic compensation in a position to which this Act does not apply.”