haha yea, it's kind of confusing...here, let me try to explain it again...
let's say the correct way to go is the left...if you ask each one what the other would say, then they'd both say right...see, if you ask the truthful guy what his lying brother would say, the truthful guy would say right since he knows his brother would lie...if you ask the liar brother what his truthful brother would say, he would say right since he is a liar...therefore, you should go left...
=)