SYMPTOM:
When a user has two addresses that have the same Name or Physcial Address, a 'Problem with duplicated address names' error is thrown when trying to add an address to the user in Strategy 10.x.

CAUSE:
This occurs because there is a duplicate name or address for that user.
ACTION:
Check the Deliveries > Addresses list to make sure there is no current address with the same Name or Physical Address. If there is a duplicate change one of the names or addresses.