(1) No contract or agreement, written or implied, or rule, regulation or other device, shall in any manner operate to relieve any employer, in whole or in part, of any obligation created by this chapter, except as provided in subsection (b).
(2) Any employer may set off from temporary total, temporary partial, permanent partial and permanent total disability benefits any payment made to an employee under an employer funded disability plan for the same injury; provided, that the disability plan permits such an offset. The offset from a disability plan may not result in an employee's receiving less than the employee would otherwise receive under this chapter. In the event that a collective bargaining agreement is in effect, this subsection (b) shall be subject to the agreement of both parties.