Anything in this division to the contrary notwithstanding, a member of the Employees’ Retirement System shall not receive credit for such service where at the time of retirement he has credit or is entitled to any benefits whatsoever for the same service under any other retirement or pension plan which is wholly or partly funded from public funds; provided that nothing herein shall be construed to apply to participation in the federal Social Security program. In the event of disqualification of such service credit, contributions made under this division by the member shall be refunded to him.