Now, that doesn't say the documents came from Snowden, only that it was contained in them. They're both likely telling the truth when Snowden says 'it wasn't from me!' and the Indy says they've not been duped. We know that the UK government has just gotten hold of these documents, but we don't know whether there's anyone sympathetic to the cause mixed in there.
There's a lot of facets to this and care is needed from both sides of the fence, but there's no love loss between The Guardian and The Independent. Maybe The Indie has been told one thing off the record that might have a nugget of truth that's been paired down by Chinese whispers, we just don't know. The Guardian is probably sanitising what they publish after what happened with Wikileaks (no one ever took blame, the password was published by them after assurances it was temporary), and would prefer another firefighting exercise.
Upshot is, The Indie revealed another piece of the puzzle in the reach of the surveillance culture that's being built.