Is it possible to play from Rekordbox library on deck 1, while from external USB on deck 2?

I just got the XDJ RR and I'm wondering if I can play a track from my computer's hard drive in Rekordbox on deck 1 in conjunction with a track from my external USB stick on deck 2. 

I can successfully play a track in Rekordbox on deck 1, load a track from the external USB stick on deck 2 and play it, but there's no sound from deck 2.