Wrong data with UNION ALL when querying different sub-directories under the same table

select count (*) from (
  select l_orderkey, dir0 from l_3level t1 where t1.dir0 = 1 and t1.dir1='one' and t1.dir2 = '2015-7-12'
  union all 
  select l_orderkey, dir0 from l_3level t2 where t2.dir0 = 1 and t2.dir1='two' and t2.dir2 = '2015-8-12') data;
+---------+
| EXPR$0  |
+---------+
| 20      |
+---------+

0: jdbc:drill:zk=10.10.100.190:5181> select count (*) from (select l_orderkey, dir0 from l_3level t2 where t2.dir0 = 1 and t2.dir1='two' and t2.dir2 = '2015-8-12');
+---------+
| EXPR$0  |
+---------+
| 30      |
+---------+
1 row selected (0.258 seconds)
0: jdbc:drill:zk=10.10.100.190:5181> select count (*) from (select l_orderkey, dir0 from l_3level t2 where t2.dir0 = 1 and t2.dir1='one' and t2.dir2 = '2015-7-12');
+---------+
| EXPR$0  |
+---------+
| 10      |
+---------+