Applicability of tds on man power supply

my client is a private limited co who provide the engineers to B co on the employment basis & our company charges salary of the engineers & pay less salary to the engineer. as per my opinion we only provide the engineer ton co B the company & directors have not any specialization in the filed of engineer. they only make a contract with co B to provide the engineer B in their Co. But co B deducted TDS U/s 194J. Whether it is correct?