A plan established by this part shall exist and serve in addition to other retirement, pension, or benefit systems established by the state of Tennessee, state agencies, counties, municipalities, or other political subdivisions. A deferred compensation plan established by this part shall not supersede, make inoperative, or reduce any benefits provided by the consolidated retirement system or programs established by any counties, municipalities, or other political subdivision thereof, or any other retirement, pension, or benefit program established by law.