A member may be entitled to benefits under Title 29 of this article other than, or in addition to, the service retirement benefits provided under this subtitle. This subsection does not apply to an individual receiving a service retirement allowance or a vested allowance from the State Police Retirement System who is: serving as a sheriff or State’s Attorney for a county that is a participating governmental unit; or elected or appointed to the General Assembly and eligible to enroll in the Legislative Pension Plan. A member is not entitled to receive a pension or retirement allowance from another pension or retirement system supported wholly or in part by the State. An individual receiving a service retirement allowance or a vested allowance from the State Police Retirement System who is elected or appointed to the General Assembly and eligible to join the Legislative Pension Plan, may only receive an additional retirement allowance from the Legislative Pension Plan.