Can you open two duplicate records, click View all properties in the left sidebar and look up the values for the properties below for both records. What do you see?
Original source data 1: additional information about the original source for the associated contact, or associated company if there is no contact, with the oldest value for the Time first seen property.
Original source data 2: additional information about the original source for the associated contact, or associated company if there is no contact, with the oldest value for the Time first seen property.
Original source type: the original source of the associated contact, or associated company if there is no contact, with the earliest activity for the deal. Learn more about contact original source values.
Best regards
Karsten Köhler HubSpot Freelancer | RevOps & CRM Consultant | Community Hall of Famer
Then it seems like these deals aren't originating from inside of HubSpot but are being created by an integration. You would have to investigate which tools your team has integrated with HubSpot and work with them to avoid the creation of duplicates.
Best regards!
Karsten Köhler HubSpot Freelancer | RevOps & CRM Consultant | Community Hall of Famer