PS2 Backups

Hi,
A friend of mine asked me if there is a way to backup larger PS2 games (Games that won’t fit on a 4.7gb disc) onto 4.7gb discs. I really don’t have a clue. :confused:

Logically you could use a dual layer disc, but they are pricey (compared to the 4.7gb). Is there a program that could split the game into 2 discs or is there dummy files (probably depends on the game) that you could delete from the image. He is using Alcohol 120% to backup his games.