No creditor so named in this proceeding shall have any right to garnishee the petitioner therein, and it shall be the duty of the employer in any case when served with a notice of garnishment against said employee, nevertheless to pay said wages to the clerk of the court aforesaid together with notice that such wages have been garnisheed together with any other pertinent facts pertaining to the case. When and in case any creditor not listed shall garnishee any wages so assigned, he shall have the right to have his cost expended in said garnishment added to the amount due him by proof to the court that said garnishment was instituted in good faith and without knowledge of said assignment proceedings.