You can import a vCard file into Handy by dragging and dropping it onto the main window. This will open a dialog showing you how many vCard files were dropped, and the total number of addresses contained in all the dropped vCards.
In this dialog you can control what to do when the same named address is in the importing vCard file and also already in Handy Address Book. Records are considered to be duplicates if they have identical names. You can choose to ignore duplicates from the importing vCard, create a new address for them, or replace the current address in Handy with them.