Season 1 was 6 discs. Counting EAF as two episodes, the discs were split 4/5/5/5/5/2.
Season 2 is 5 discs, and split 5/4(+extended episode)/5/5/3.
Actually the discs do have a unique number on each of them, at least all my discs had a different number. They were similar so there might be a lot number embedded in the actual disc number, but the numbers on all the discs in the set were not the same.