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When two customer profiles are merged in Maestra, their unique identifiers don’t disappear. Here’s exactly what happens to each one, and how you can still use the old identifiers afterward.

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The primary unique ID

The primary unique ID kept after the merge is the one that belonged to the priority customer. That ID becomes the active identifier on the merged profile going forward.

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The secondary identifier

The second customer’s identifier isn’t deleted. It’s preserved in the profile’s change history. The archived identifier stays functional. You can still use it when:
  • Calling the Maestra API
  • Uploading or importing customer data
In other words, even though it’s no longer the primary ID, it continues to resolve to the merged customer profile.

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MaestraId

All MaestraId values are also archived in the change history and remain available for data exchange. The system doesn’t apply any priority rule for choosing a specific MaestraId — any of the archived MaestraId values can be used to reference the merged profile.
Both the secondary unique ID and the archived MaestraId values stay usable after the merge. You don’t need to update your integrations to swap one ID for the other right away.

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Important limitation

If the unique ID configuration has the Don’t merge customers with different IDs option enabled, lookup by archived identifiers is not available. In that case, only the active primary ID will resolve to the customer profile — archived IDs will not.
Before enabling Don’t merge customers with different IDs on a unique ID, check how your integrations rely on archived identifiers. Turning this on will break any lookups that depend on resolving old IDs to a merged profile.