I thought they wanted to stop copying so people go out and actually buy the film.
It's not illegal to make a copy provided you have permission from the copyright owner. The people setting up Ultraviolet know that they are competing with piracy, and a major reason why people do pirate is convenience. So they have tried to make Ultraviolet convenient, and generally tried to give customers licence to do what they would have done anyway. They know that hoping to sell two copies of The Hobbit
to the same household is unrealistic. This way they've at least sold one.
I see it as a positive move.