How do I remove duplicate contacts?

How duplicates are handled

• CSV import: rows whose address already exists, or appears earlier in the same file, are skipped. The existing contact is not updated and does not get the import's tags.
• Adding one by one and the API refuse an address that already exists.
• To add an existing contact to a new list, select it in Contacts and use Tag Contacts.
• To update existing contacts' details, edit them in Contacts.