Requiring that the average weekly wages from employments of a covered employee who, at the time of an accidental personal injury, was concurrently employed by more than one employer be combined for purposes of computing the average weekly wages under certain circumstances; requiring that the Subsequent Injury Fund or the Uninsured Employers' Fund reimburse an employer for certain compensation paid by the employer; and requiring the average weekly wage for certain covered employees to be recalculated under the Act.