How to manager duplicate Client CONTACTS

Hi, we have a number of client 'CONTACTS' who need to be set-up twice on Z. Recruit, this is because they are responsible for more than one site / location. Our issue is that Z Recruit only allows us to have one email address per CONTACT we need to find a way of flagging that the second CONTACT with the same name, but without the email address does not keep appearing as being a 'blank' email address on our system. Are you able to assist me?