Duplicates are commonly created by entering a new name at the time of making a reservation versus searching to see if there is an existing profile to build the reservation for the guest.
Although a profile cannot be deleted if it has been created/used in a current reservation whatever status. However, duplicate profiles can be merged under one condition: they need to be exactly identical (wording, upercase/lowercase letters, ponctuation, ...).
Two fields will prevent the merge and cannot be in more than one profile being merged: the Driver License and the Franchise Member fields.
Path: Sales & Marketing > Guest Profiler > History Merge