In addition to being able to merge end user profiles individually we offer the ability to do this in bulk. This is only available to users with the ‘Administrator’ role and can be found by clicking on your avatar in the bottom-left corner and selecting 'Powertools'.
The 'Merge All Duplicate Contacts/Users' option works in the follow way:
All end users with the same email addresses are found and grouped. We then identify which end users are "mergeable". Any pair of end users are mergeable if they aren't related to different companies and they don't have different external ids. If one or both sides have empty companies/external ids, then they're still considered mergeable.
Unmergeable end users are updated to have mutual references to each other and we show a “duplicate” mark on them in the list of end users.
In the top right-hand corner of the end user profile you can choose between any of the end users with the same email address.
Mergeable end users are merged into one new end user and all of the old end users are removed.
Single-data fields (e.g. externalId, company, name, description) are set based on the end user with a non-empty value for that field. If both end users have a value, then the first value is chosen without any order. For list-like fields (e.g. tags, personas), the data is merged and items from all end users are kept.
The maximum amount of duplicate end users merged in one process is 50. If you have over 50 duplicate end users you will need to run this process multiple times.