Quorum alius alia causa illata

This is from Gallic Wars, Book I, chapter 33. The full sentence is:

"quorum alius alia causa inlata, quam sibi ad proficiscendum necessariam esse diceret, petebat ut eius voluntate discedere liceret"

I understand everything except the "alius, alia" part. I know that when alius is doubled it means "the one...the other", but in this case a nominative "alius" is followed by "alia" which is in an ablative absolute clause of "alia causa illata". I am just so confounded, please help me.