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    Practical guide

    CRM contact deduplication: match, review, merge

    Find duplicate contacts, check who each record represents, and review what a merge will change. Start with a small batch before cleaning a whole database.

    Tiago Ferreira
    Tiago F.
    Writer · Updated 13 September 2026

    What is contact deduplication?

    Contact deduplication finds records that may describe the same person, checks the match, and combines confirmed duplicates. A shared email address, name, or phone number is a clue. Check the person behind it before merging.

    How to find duplicates without mixing up people

    Group likely matches using the fields your CRM supports. Keep record IDs and source-system IDs in your review so you can trace each candidate back to its source.

    • Email

      Compare normalized addresses, then check names and company history. Shared inboxes such as sales@example.com can represent several people. A person may also use more than one email.

    • Name and company

      Use similar names to find candidates for review. Two people can share a name at the same company, and a job change can make one person look like two.

    • Phone and domain

      Check country codes and shared switchboards. A company domain can cover several subsidiaries. Similar-looking domains alone do not prove two companies are the same.

    A checklist before you merge

    Export the fields and record IDs you need, review your CRM's merge rules, and test one confirmed pair. An export may not include every association or restore a merge.

    • Confirm the person and the surviving record

      Ask the record owner when identity is unclear. Choose the record to keep and review conflicting email, company, owner, and phone values.

    • Check history and linked work

      Compare activities, notes, deals, tasks, files, and company links before and after the test. Record what transfers and what needs manual repair.

    • Check consent and connected systems

      Review subscription status, opt-outs, active outreach, and sync mappings. A merge can affect workflows or linked records in another tool.

    • Verify recovery before a batch

      Check whether undo exists and what it restores. HubSpot says merged records cannot be unmerged. Its merge documentation also lists workflow and sync effects.

    Stop the same duplicates coming back

    Search before adding contacts. Keep import columns consistent, use source record IDs where supported, and test each integration's matching rules. Review new candidates after imports or sync changes. Set the regular review schedule from the duplicates you actually find.

    • Measure your own duplicate rate

      Count confirmed extra records, not suggested pairs. If 100 records describe 90 distinct people, there are 10 extra records: a 10% duplicate rate. Track that number after each review.

    Review duplicates in Lumenbase

    The import preview uses the duplicate keys you select and lets you choose whether a matched row is skipped, updated, or created. Review the selected action before continuing.

    • Choose what to keep

      The duplicate review lets you select a surviving record. For a two-record group, conflicting fields can be compared and chosen individually.

    • Check the result

      Open the surviving contact and verify its linked work. Eligible merges can be undone from hygiene merge history within 30 days. Some large merges cannot be undone. Check connected tools separately.

    Common questions

    Merge only after confirming both records describe the same person. Keep separate records when they represent different people. Archiving a duplicate leaves its history separate; check whether that matches your retention process.

    Email is useful for finding candidates. Shared or reassigned inboxes need extra review, and one person can have several addresses. Check names, company history, and source IDs before combining records.

    Measure your own database. Review suggested matches, count confirmed extra records, and divide by the number of records checked. A generic percentage cannot tell you how many records are safe to merge.

    It depends on the CRM and the merge path. In Lumenbase, eligible merges can be undone from hygiene merge history within 30 days. Some large merges cannot be undone. Check the available action before a batch and verify connected systems separately.

    Sources and setup guides

    External sources checked on 13 September 2026.

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