Whenever an individual is entitled to benefits under this part but there is a dispute whether such benefits are payable from the Disability Fund or from one or another voluntary plan, benefits shall be paid to the individual, pursuant to authorized regulations, from the source against which his claim was first filed, at not less than the Disability Fund rate, pending the determination of the dispute. The appeals board may prescribe by regulation the time, manner, method, and procedure through which such disputes may be determined by administrative law judges and the appeals board. If it is finally determined that the benefits should have been paid from one of said sources other than the one which paid the benefits, reimbursement shall be promptly made from the Disability Fund or the voluntary plan, as the case may be, and the claimant shall be promptly paid the accumulated excess, if any, to which he is entitled. Reimbursement shall also be made to the extent of actual liability for benefits from one to another of the above mentioned sources when it is determined that benefits have been paid in error from one source which should have been paid from another.