Ahhhh thanks! So that's where the trick starts!
Funny isn't it? They need a budget version *much later* issued to release a 1-disk version, which can/could save people with only 1 drive lots of trouble.
I think there's a right for a question: Why not on the initial release either?
Could even have saved some MATERIAL because one disk per box is cheaper than two, in terms of production costs.