Every health insurance policy issued under a group insurance plan and by an insurance company, hospital service corporation, medical service corporation, health care center or fraternal benefit society, delivered, issued for delivery or renewed in this state shall allow the spouse of any employee participating in such or any other group insurance plan offered by the same employer to be covered as an employee in addition to being covered as a dependent of such participating employee, except that benefits provided under such combined coverage of the employee as an employee and as a dependent shall not be in excess of one hundred per cent of the charge for the covered expense or service. The provisions of this section shall apply only where spouses are employed by the same employer and by reason of their employment are both participating in a group insurance plan. Nothing in this section shall alter or impair existing group health insurance policies or contracts that have been established pursuant to an agreement that resulted from collective bargaining, and the provisions required by this section shall become effective upon the next regular renewal and completion of such collective bargaining agreement.