Over the course of using a CRM system, duplicates tend to get created by accident. Sometimes it is due to users entering records twice, sometimes it is due to clients entering forms more than once. Zoho CRM comes with a Deduplication method built in. Deduplication can be used for Leads, Accounts, Vendors, and Contacts.
See animation below on how to start the deduplication process. Choose the criteria and combinations you want to check duplicates for. Deduplication
This process runs on the server - you will be notified once it has completed. If records need to be verified, the system will provide a link to the records requireing review. In the records that are different between the copies, you can choose which data to keep, and which to delete in the merging process.
For more information on the deduplication process, see here: