CREATE TABLE TEST
(
ID INTEGER NOT NULL PRIMARY KEY,
KOD VARCHAR(5)
);
COMMIT;
INSERT INTO TEST(ID, KOD) VALUES(1, 'abc');
INSERT INTO TEST(ID, KOD) VALUES(2, 'abc');
COMMIT;

now we have 2 rows in table
and delete in ascending oreder
DELETE FROM TEST T WHERE EXISTS(SELECT * FROM TEST T2 WHERE T2.ID<>T.ID AND T2.KOD=T.KOD) ORDER BY T.ID ASC
COMMIT;
one row affected ..

SELECT * FROM TEST;
one row selected ID=2 KOD='abc'

clear table
DELETE FROM TEST;
COMMIT;

once again insert the same records
INSERT INTO TEST(ID, KOD) VALUES(1, 'abc');
INSERT INTO TEST(ID, KOD) VALUES(2, 'abc');
COMMIT;

now we have 2 rows in table
and delete in descending oreder

DELETE FROM TEST T WHERE EXISTS(SELECT * FROM TEST T2 WHERE T2.ID<>T.ID AND T2.KOD=T.KOD) ORDER BY T.ID DESC
COMMIT;
two rows affected!

SELECT * FROM TEST;
empty result set!

you see that deleting with asc and desc do big difference but here should not
with asc sorting you delete 1 record which is ok
and with desc sorting you delete2 records(all) which is wrong