When any railroad company has what is usually called a relief department for its employees, the members of which are required or permitted to pay some dues, fees, moneys or compensation to be entitled to the benefits thereof upon the death or injury of the employee, a member of such relief department, such railroad company shall pay to the person entitled to it the amount it was agreed the employee or his heirs-at-law should receive from such relief department. The acceptance of such amount shall not operate to estop or in any way bar the right of such employee or his personal representative to recover damages of such railroad company for injury or death caused by the negligence of such company, its agents or servants, as provided by law and any contract or agreement to the contrary shall be ineffective for that purpose.