Efficiently Joining Same Table Twice

My main table has the following structure:

t1 (id_primary, id_secundary, name) i.e. [(1,1,"name1"), (2,1,"name2")]

I want to join this table with the following second table:

t2 (id_primary, id_secundary, value) i.e. [(1, NULL, "value1"),
(NULL,1,"value2")]

The join should first try to find a match on id_primary and only if that
fails it should find a match on id_secundary. Every row in t1 is matched
against a single row in t2.

The following query works:

select
a.name, isnull(b.value, c.value)
from
t1 a left outer join t2 b on a.id_primary = b.id_primary
left outer join t2 c on a.id_secundary = c.id_secundary

I'm wondering though if it would be possible to write a query that only uses
t2 once, since it actualy is quite a complex query that is calculated twice
now. Any ideas (besides using a temp table)?