This app has the feature of deleting duplicate contacts in a group. It detects the contacts with similar phone number and merges it together to create a single contact. It also detects contact having duplicate numbers, emails, websites, etc and gives option to either remove duplicates or merge it into on single contact.

This app has the easiest way to backup and restore your contacts all from your phone without needing a computer or synchronisation. You can backup all your contacts with a single touch and send them to yourself as a .vcf attachment via AirDrop.