Avoid creating duplicates

An import either adds every row as a new record or updates records you already hold. The choice is made during mapping, and it is what decides whether re-running a file repairs your data or doubles it.

• ⟦Skapa alltid Nya Poster⟧ — every row becomes a new record, whatever already exists. Right for a genuinely new list.
• ⟦Uppdatera Befintliga Poster (Upsert)⟧ — a row matching an existing record updates it instead of adding another. Right for refreshing data you already have, and right for re-running a file you imported before.

Matching needs something stable. An update can only find the existing record if you tell it what to match on, and the field you pick decides whether it works. An organisation number or an email address identifies a record reliably. A company name does not: "Acme Ltd", "Acme Limited" and "ACME LTD" are three different strings, and only one of them matches.

It already happened

If an import has produced duplicates, do not just delete the new records — some may have picked up notes, activities or emails since they arrived. Use the duplicate detection built into the customer and contact lists, which finds matching records and merges them so the history from both survives.

Then fix the cause before importing again. It is almost always one of two things: the run was set to always create new when it should have been set to update, or it was set to update but matched on a name.

Before any repeat import, run five rows and confirm they updated the records you expected instead of creating fresh ones.