Hi Elizabeth,
Thank you for your question!
There currently isn't a way to merge registrations. As Michele mentioned above, there are a few manual steps you can take to cancel the duplicate registration and send the registrant an email letting them know you made the update.
The platform does have the functionality of merging contacts in the address book. I would recommend reviewing this article if you want to make sure the person doesn't have two contact records: Merging Contacts
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Sydney Langer
Senior Customer Success Advisor
Cvent
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