OR query with ORDER BY don't work as expected

A query with Or and having order by along with limit Don't reproduce results as per order mentioned. 

e.g. 

Let content be:

"/UnionQueryTest1/node0",
"/UnionQueryTest/node0",
"/UnionQueryTest1/node0/node1",
"/UnionQueryTest/node0/node1",
"/UnionQueryTest1/node0/node1/node2",
"/UnionQueryTest/node0/node1/node2",
"/UnionQueryTest1/node0/node1/node2/node3",
"/UnionQueryTest/node0/node1/node2/node3"

each node having x = number in node name.

SELECT idn1.* FROM [nt:base] as idn1 WHERE ISDESCENDANTNODE([/UnionQueryTest]) OR  ISDESCENDANTNODE([/UnionQueryTest1]) ORDER BY idn1.[x] ASC

result should be  same as above mentioned where as current result come out to be

/UnionQueryTest1/node0
/UnionQueryTest1/node0/node1
/UnionQueryTest1/node0/node1/node2
/UnionQueryTest1/node0/node1/node2/node3
/UnionQueryTest1/node0/node1/node2/node3/node4
/UnionQueryTest/node0
/UnionQueryTest/node0/node1
/UnionQueryTest/node0/node1/node2