To merge two customers/tenants, click on the customer/tenant record, click on Actions > Admin Tools > Merge.
Search for the duplicate address. Click to confirm the merge.
Please note, merge should only be used when you've duplicated accounts. It shouldn't be used for any other reason. Merges cannot be undone (not even by CommuSoft support!)
Please note: If you merge Customer 1 into Customer 2, the address and details of Customer 2 will be retained but all other information will be retained from both customers.