Symptoms

Confluence Cloud 'People' directory will feature the same user account multiple times:

Alternatively, using the mention functionality will return multiple results for the same user:

Cause

The multiple entries are due to duplicated values in the USERINFO table of the Confluence Cloud service.  The tables are not visible to Cloud users as part of Compare Atlassian cloud vs server. 

Resolution

• Raise a support request at support.atlassian.com you can reference Duplicates in the People Directory as the solution.

• Provide a maintenance window of 15 minutes to allow the above guide to be completed. Confluence will be unavailable during this period.

• Support will advise once maintenance applied and duplicates removed.

The bug is tracked at CONF-30050 - Getting issue details... STATUS