Overview
Even if you are very diligent, duplicate contact records can occasionally still get created in CiviPlus, either via manual data entry, imports, or online self-service webforms. To help maintain data quality, CiviPlus provides a set of tools for identifying, preventing, and resolving duplicate contacts in a controlled and auditable way.
CiviPlus does not automatically merge duplicates without checks. It uses configurable rules to either flag potential duplicates for review or safely merge records in specific automated scenarios.
How Duplicate Contacts Can Get Created
Duplicate contacts typically get created in situations such as:
A Civi user creates a new contact without realising it already exists
A person signs up online using a different email address or spelling
Contacts are imported without appropriate matching rules
Data is migrated from multiple external systems
Because these situations are common, CiviPlus assumes duplicates will occur and focuses on helping administrators manage them effectively rather than trying to eliminate them entirely .
Deduplication (Dedupe) Rules
What are dedupe rules
Dedupe rules specify how CiviPlus decides whether two contacts should be considered potential duplicates. A rule is made up of:
One or more fields to compare, such as email, name, or address
A weight for each field, which is assigned if there is an exact match
A threshold score that determines when a match is considered a duplicate. This compared to the sum of the weightings assigned for each field compared.
When two contacts meet or exceed the threshold score, they are flagged as potential duplicates .
Dedupe rules are configured separately for each contact type:
Individuals
Organisations
Households
Types of dedupe rules
CiviPlus supports three types of dedupe rules, each used in different contexts.
Unsupervised rules
Used in automated processes
Designed to be strict and reliable
Applied during:
Online registrations
Event, membership, and contribution signups
Contact imports
If a match is found, CiviPlus assumes the records are the same and merges or updates automatically, depending on the context.
Supervised rules
Used when a user is present to review the result
Applied when contacts are added or edited via the user interface
If a match is found, the user is warned and can choose whether to continue or edit the existing contact
These rules are usually broader than unsupervised rules because human judgement is involved .
General rules
Used for proactive data cleanup
Applied when scanning the database for duplicates
Multiple general rules can be created for different matching strategies
Identifying Duplicates
Automatic checks
CiviPlus automatically checks for duplicates in several scenarios:
When contacts are created or edited via the UI
When contacts are created through online forms
When contacts are imported
Which dedupe rule is used depends on the context and contact type .
Manual scanning for duplicates
Administrators can also actively search for duplicates by going to:
Contacts → Find and Merge Duplicate Contacts
From there, you can:
Choose a dedupe rule
Scan all contacts or a specific group
Review a list of potential duplicate pairs or groups
This process allows systematic data cleanup without relying solely on automated checks .
Merging Duplicate Contacts
The merge process
When merging two contacts:
One record is selected as the primary contact
The other record is merged into it and then deleted
Related data is preserved, including:
Activities
Contributions
Memberships
Events
Cases
Tags and group memberships
During the merge, users can choose which values to keep when fields differ. Data is colour coded to highlight matches, differences, and additive data such as activities and tags .
Marking contacts as not duplicates
If two contacts are incorrectly flagged as potential duplicates, they can be marked as Not a duplicate.
These pairs are excluded from future dedupe results
Exceptions can be reviewed later from the dedupe screen
This helps prevent repeated false positives .
Batch merging
For large datasets, CiviPlus supports batch merging:
Merge all duplicates found by a rule
Merge selected duplicates only
Skip records where there are data conflicts
Batch merging is powerful but risky and should only be used after testing and data backup, as merges cannot be undone without database logging enabled .
Best Practices
Review and tune dedupe rules before large imports
Keep unsupervised rules strict to avoid false merges
Use supervised and general rules for cleanup and review
Always back up data before batch merging
Merge manually when data conflicts require judgement