Hello,
I already have owned SMB on steam since release in 2010.  I recently got a copy of the Ultra Edition on disc.  I can install the game with the disc, but I will not get the Alien Homonid.  Steam will not allow me to register the game again either.  As I play this game across a few systems (a few of which do not have disc drives)it would be nice to play without having to worry about keeping the disc handy.  I'm still loving this game after almost two years since release. Can't wait to see more.
thank you