Yup. I am guessing these new releases are based off of the same near- final versions from the 2006-2008 stuff. The General is probably the version that was played at that party, with the guitars and bass removed and redone by Slash and Duff. They are just replacing the multitracks, it seems. Works for me, now.
What proof could there be? Songs just show up on streaming sites when they come out, these days. Hard Skool just appeared, all the sudden. It was out in New Zealand first. Absurd came out at 12am EST and also just appeared