Multiple unnests in query

Good night,

Is this first query expected behavior? If so, what is the rationale? I
would have expected nine rows returned (as in my second example).

Regards,
Aron Widforss

SELECT
unnest(ARRAY[1, 1, 2]) AS unnested1,
unnest(ARRAY[3, 3, 4]) AS unnested2
;
unnested1 | unnested2
-----------+-----------
1 | 3
1 | 3
2 | 4
(3 rows)

SELECT
unnest(ARRAY[1, 1, 2]) AS unnested1,
sec
FROM (SELECT 3 AS sec UNION ALL
SELECT 3 AS sec UNION ALL
SELECT 4 AS sec) test
;
unnested1 | sec
-----------+-----
1 | 3
1 | 3
2 | 3
1 | 3
1 | 3
2 | 3
1 | 4
1 | 4
2 | 4
(9 rows)