Dublettenerkennung beim CSV-Import von Kontakten

I want SAGA to be able to recognize duplicates when importing contacts via CSV. I have a large existing customer base (600 contacts) and frequently receive updated lists that include new customers (e.g., 80 new contacts in a list of 680). I need SAGA to automatically identify the 600 existing contacts and only import the 80 new ones to avoid creating duplicates. This is a recurring process and manual separation is time-consuming.