No provision of this chapter shall be construed to authorize any member, credited with service in more than one entity and who is eligible for a disability allowance, whether service connected or nonservice connected to receive an amount from one county that, when combined with any amount from other counties or the Public Employees’ Retirement System, results in a disability allowance greater than the amount the member would have received had all the member’s service been with only one entity.

In cases of service-connected disability allowances only, the limitation on disability allowances provided for in this section shall apply to service-connected disability allowances payable to those who, after being employed with another county or an entity within the Public Employees’ Retirement System, become employed by a second public entity on or after January 1, 1984.

Each entity shall calculate its respective obligations based upon the member’s service with that entity and each shall adjust its payment on a pro rata basis.