Players of Rocksmith 2014 on the PC/Mac were experiencing issues with their previously purchased RS1 DLC showing up in Rocksmith 2014. An update has just been pushed to Steam that resolves this issue. Please update Rocksmith 2014 and keep in mind a Steam restart might be required. Please let us know if this resolves the issue or if you notice any other problems relating to this.
Shiny Rocksmith 1 DLC in Rocksmith 2014 PC.