Avoiding Duplicate Records

Avoiding Duplicate Records

We have created an online application within Zoho, however, many of our older records were added prior to this application being created. I'd like to send an email to those Candidates and have them update their application. However, my testing shows that Zoho Recruit won't recognize the email when they create their Log In (I've checked the box requiring a log in). What happens is they see an empty application rather than their record. I don't want to have 2 records for each of these Candidates. I appreciate your help.