Storing applicant details

After an issue with a recruitment company charging us fees for recruiting someone via another agency when they had originally sent the person to us for interview, we are now looking to have a central database of all people who apply and/or are intervied by us.

Am unsure what information from a CV to use as a reference (other than name) incase we get lots of “John Smiths” etc

Obviously can’t use DOB and address only effective if the person doesnt move.