It's not entirely clear why you expect to get the 3 and 4 values twice, but you could create something like that using UNION ALL eg (using Chris' sample data)

SELECT *

FROM #table1 t1

LEFT JOIN #table2 t2 ON t1.id = t2.id1

UNION ALL

SELECT id, value, NULL, NULL

FROM #table1 t1

WHERE NOT EXISTS ( SELECT * FROM #Table2 t2 WHERE t1.id = t2.id1 )