Salesforce Says Duplicate Data Exists and Blocks My Data From Being Imported

Duplicate Rules and Matching Rules in Salesforce

Salesforce editions include Duplicate Rules and Matching Rules, designed to help maintain clean data and ensure that users rely on a single, trusted record, often referred to as the "source of truth."

The goal of these features is to prevent situations where multiple records represent the same entity. Duplicate data can cause confusion over which record should be used. Matching Rules and Duplicate Rules work together, and in some cases, may block duplicate entries altogether.

This functionality applies to Accounts, Contacts, and Leads.

Standard Rules Provided by Salesforce
- Accounts
- Contacts 
- Leads 
- Leads with Accounts 

How to Interpret Rules

For example, an Account may have the following rule:
(Account Name AND Billing Street) OR (Website AND Phone)
This means that if a new account record is created (manually or through data import) and it shares the same Account Name and Billing Street OR the same Website and Phone Number as an existing account, Salesforce will flag it as a potential duplicate.

Deactivating Duplicate Management

Note: Deactivating these rules is not recommended, as it can result in duplicate records across your system and create confusion for your team. Proceed only if absolutely necessary.

Using Setup

- Click the gear icon in the upper right and select Setup.
- In the Quick Find box, search for Duplicate Rules, then click Duplicate Rules.
- Open the relevant Duplicate Rule and click Deactivate.
- In the Quick Find box, search for Matching Rules, then click Matching Rules.
- Deactivate the appropriate Matching Rule.

Using Data Import Wizard

If a Duplicate Rule is set to Allow with Alerts, the import may trigger the error:
DUPLICATES_DETECTED: Use one of these records?: — (the error message text is defined in the active Duplicate Rule)