If an employee receives an injury for which compensation is payable while he is still receiving or entitled to compensation for a previous injury in the same employment, he shall not at the same time be entitled to compensation for both injuries, but if he is, at the time of the second injury, receiving compensation under the provisions of § 65.2-503, payments of compensation thereunder shall be suspended during the period compensation is paid on account of the second injury, and after the termination of payments of compensation for the second injury, payments on account of the first injury shall be resumed and continued until the entire amount originally awarded has been paid. However, if, at the time of the second injury, he is receiving compensation under the provisions of § 65.2-502, then no compensation shall be payable on account of the first injury during the period he receives compensation for the second injury.