DB Error: constraint violation

INSERT INTO cart (id_cart, id_user, id_session, id_plateforme, id_plateforme_pays, status, date) VALUES (6328212, 0, '0da9806e79965778aacdc72c95620e7e', '0', '5', 'session', NOW()) [nativecode=1062 ** Duplicate entry '6328212' for key 1]