Checks in payment for claims pursuant to any health care service contract for health care services provided by persons licensed or regulated under chapters
18.25, 18.29, 18.30, 18.32, 18.53, 18.57, 18.64, 18.71, 18.73, 18.74, 18.83, or
18.79 RCW, as it applies to registered nurses and *advanced registered nurse practitioners, where the provider is not a participating provider under a contract with the health care service contractor, shall be made out to both the provider and the enrolled participant with the provider as the first named payee, jointly, to require endorsement by each: PROVIDED, That payment shall be made in the single name of the enrolled participant if the enrolled participant as part of his or her claim furnishes evidence of prepayment to the health care service provider: AND PROVIDED FURTHER, That nothing in this section shall preclude a health care service contractor from voluntarily issuing payment in the single name of the provider.