Duplicate In Form

DECLARE
    A NUMBER(1):=0;
    F_NAME VARCHAR2(35);
BEGIN
    F_NAME:=:MM_LC_ORDER_MAPPING.ORDER_DESC;
    FIRST_RECORD;
    WHILE :MM_LC_ORDER_MAPPING.ORDER_DESC IS NOT NULL LOOP
        IF F_NAME=:MM_LC_ORDER_MAPPING.ORDER_DESC THEN
            A:=A+1;
        END IF;
        NEXT_RECORD;
    END LOOP;
    PREVIOUS_RECORD;
    IF A>1 THEN
        MESSAGE('DUPLICATE RECORD');
        MESSAGE('DUPLICATE RECORD');
    ELSE
        NEXT_ITEM;
    END IF;
    END;