The way I read what you want is that ADMIN.ANAMAGA_TMP is a log of only the new rows added to ADMIN.ANAMAGA. If this is true, then your trigger would be:
CREATE TRIGGER ADMIN.REPLICA AFTER INSERT ON ADMIN.ANAMAGA REFERENCING NEW AS n FOR EACH ROW MODE DB2SQL INSERT INTO
ADMIN.ANAMAGA_TMP VALUES (n.CODICE,n.DESCRIZION,n.TIPO)
Andy