Welcome to the community, @Stephane_Hotte! :grinning_face_with_big_eyes: Airtable is more of a hybrid database/spreadsheet than a pure database. Internally, it does store a unique ID for every record, which you can see using the
RECORD_ID() function in a formula field. However, as you’ve noticed, it does not prevent duplicate entries in the primary field. My guess is that they opted for the internal unique ID as the main identifier vs using the actual data entered into the primary field so that they could make the system more user friendly and appeal to a wider audience.