*De-duplication is a feature we have been offering for a long time. In the latest version, this feature has been removed as it’s not in line with our key value propositions. Especially since it’s a feature that native address book and Contacts accounts also supports quite well.
Depending on where you keep your contacts (Google, Outlook, iCloud, etc.) there are ways to remove duplicates right there, and you can write to us in firstname.lastname@example.org for further direction.