I let an app clean duplicate contacts and spent Sunday rebuilding my aunt

My contacts list had reached the stage where one person could appear as “Aunt Maria,” “Maria cell,” and a bare phone number imported from an old account. A cleanup app offered to merge duplicates automatically. I reviewed the first few suggestions, became overconfident, and approved the batch.

The app did reduce the total. It also combined my aunt with a different Maria from a neighborhood group because they shared an old landline number in separate notes. One person's email disappeared from the main card. Several labels changed from mobile to other. Nothing was catastrophic, but the list became tidier and less trustworthy.

I had assumed merging meant collecting every field under one name. In reality, conflicts require choices, and software can make the wrong choice neatly. The cleanup app had a preview, but I treated it as ceremonial.

I stopped editing and exported a copy of the current contacts. I also found an older account-level restore option, but I am not using it until I understand what period it would roll back and what newer contacts might disappear. For now, I am repairing the few people I can verify from messages and emails, starting with family and emergency contacts.

My next cleanup will be smaller: identify the accounts supplying contacts, choose a primary source, review ten proposed merges at a time, and check namesakes with shared household numbers carefully. A smaller list is not useful if I no longer trust it.

How do you clean years of duplicate contacts without turning an automated merge into an archaeological project? What should be backed up, and which fields deserve a manual look before any bulk action?