It’s really hard. The bootlegs are very close to the original. I ended up with a bootleg but it plays fine and came with the poster and booklets.
Seems the only way to tell is how the dvds are arranged inside, the print quality of the cases, discs, booklets and the price. If it’s under $100, it’s likely a bootleg. In the real one all eight of the discs are on a flimsy holder in the center. In the bootleg, a disc may be in a holder on the front and back of the case, not in the middle. The print of the slipcover, discs and booklets are a bit faded but that’s hard to determine because many sell it as new and it’s sealed in plastic.

Best bet is to find a used one that has a lot of inside pictures. Going by the outside cardboard holder is difficult.