Two of either is one, one of each is the other.
To what do I refer?
Note: There are two different solutions.
Okay, two possible solutions:
Solution 1:
0 and 0. Two of either (0+0) is one of the 0s, one of each (0+0) is the other 0! Kind of cheating, I know.
Better Solution 2:
1 and -1. Two of either (1*1 or -1*-1) is one (1), one of each (-1*1) is the other (-1).
Possible Solution 3 (thought of independently of Andreas's answer =P):
True and False, split by "==". (True == True) is True, (False == False) is True, (True == False) is False.
Another answer:
$\frac{1}{2}$ and $\frac{1}{2}$. Two of either of these is $1$, and one of each (i.e. each one of them) is the other one of them.
I suspect the two solutions you intended were this and @VictorHenry's second solution.
If we're free to pick operators, then:
Exclusive OR: true XOR true = false, false XOR false = false; false XOR true = true