Originally Posted by
UNITED959
What is the reasoning for this??

I've got a similar situation:
MEL-...lots of places...-LAX-SYD-MEL booked as an economy star alliance award, and
LAX-SYD-MEL[-AKL-...-SFO] booked in CNZ in the way you might guess from the excitement of last month.
I'm hoping the double booking of LAX-SYD-MEL doesn't cause any trouble. Should I check in for both and visit my empty seat in Y?