SELECT DISTINCT TWO columns not ranged
A more efficient (and somewhat shorter) version of what Jon of All Trades mentioned in his answer could be something like this:

SELECT DISTINCT 
CASE WHEN A &lt; B THEN A ELSE B END AS value1,
CASE WHEN A &lt; B THEN B ELSE A END AS value2
FROM T


Of course if you had to only check for tuples that contain 1, you would add something like WHERE A = 1 OR B = 1