Resolve Duplicate External IDs Before CRM Imports
Quarantine conflicting external IDs, establish namespace and entity scope, and test reviewed resolutions without arbitrarily overwriting existing records.
10/23/20263 min read
Two rows arrive with the same external ID but different companies. The importer may reject one, overwrite one with the other, or follow a configured matching rule. None of those behaviors resolves the underlying identity question. Choosing the first row, the newest file, or the most complete record can attach research and contact history to the wrong organization.
Quarantine duplicate keys before import. The useful artifact is a conflict record that preserves both candidates, explains the scope of the identifier, and records who is authorized to resolve the collision. A technical uniqueness constraint detects a problem; it does not decide which business fact is true.
Confirm what the external ID actually identifies
Ask who issued the value, which object it names, whether uniqueness is global or local, and whether IDs can be recycled. The value 187 may be unique within one provider's branch table but meaningless without that namespace. A company ID and a contact ID can share the same characters without referring to the same object.
Salesforce documents external-ID fields as storing identifiers from other systems for supported matching workflows. Check the selected object, import tool, and uniqueness configuration. Do not equate an External ID attribute with proof that the upstream issuer has supplied a unique, correct business key.
Distinguish an exact duplicate record from a conflicting use of the same key. The first may be a repeated export. The second needs identity review even when the names differ only slightly.
Use a conflict ledger instead of a winner column
In this fictional dataset, provider Cedar assigns account key C-771 to two source rows. Row X11 describes North Dock Services, while X12 describes North Dock Holdings. The reviewer cannot assume a rebrand, parent relationship, or spelling variant.
Conflict reference: K09; source namespace: Cedar account directory; key: C-771.
Candidates: X11 and X12; retain their separate source references and observation dates.
Destination match: existing account A660, currently labeled North Dock Services.
Proposed import effect: both rows would target A660 if allowed through unchanged.
Decision status: held; identity steward assigned; no field overwrites authorized.
Required evidence: provider clarification and permitted corroboration of entity identity.
Keep only fields needed for the decision. A full duplicate of every contact note is unnecessary if the conflict concerns company identifiers. Link to controlled source material rather than distributing the whole dataset to everyone reviewing the import.
Resolve the cause, not just the symptom
If the provider confirms a duplicate export of the same entity, document how the two rows' differing fields are reconciled. Choosing a surviving row still requires field-level decisions about freshness, provenance, and restrictions. Preserve any applicable stop requests and associations.
If the provider confirms an ID reuse, retain the old entity's history and introduce the supported new identifier or versioned mapping. Do not rewrite historical records to make the collision disappear. If the values belong to different namespaces accidentally combined in one column, repair the namespacing and test the downstream key length and matching behavior.
If evidence remains inconclusive, keep both candidates held. A high import-completion target is not a reason to manufacture certainty. The business owner can decide whether the rest of the independent batch may proceed, but should not silently exclude K09 from the report.
Test the approved resolution against existing records
Build a synthetic pilot with one repeated row, one true collision, one missing key, and one legitimate key from a different namespace. State which records should update, which should remain held, and which should create new records if that mode is authorized.
For K09, inspect the destination before and after the approved correction. Verify ownership, related contacts, open activities, and any source mappings affected. A corrected display name does not prove that the right entity survived. Re-run the original duplicate input in the test environment to confirm the conflict cannot silently recur.
The release note should name the root cause, evidence, field decisions, mapping change, and unresolved candidates. Keep a stable link from the old key to its reviewed treatment when retention is justified. Future operators need to understand why an apparently duplicate identifier was rejected, rather than removing the safeguard when it interrupts the next import.
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