Section 8. If two or more cases are tried together in the supreme judicial court, in the superior court, in the housing court of the city of Boston, in the western division of the housing court department, the northeastern division of the housing court department, the southeastern division of the housing court department, in the housing court of the county of Worcester or in a district court, the presiding justice may reduce the witness fees and other costs; but not less than the ordinary witness fees and other costs recoverable in one of the cases which are so tried together shall be allowed.