I doubt Sony implemented that. I believe it would be discovered already if it was possible. I think you could test it, by hooking two HDDs, set one to master, second to slave and run HDL, see if master HDD is detected, then shut down, swap master/slave jumpers (jumpers only, don't swap them on cable) and see if second, previously slave HDD is detected.
That might just prove the Jumpers work. Unless there is a program that I can directly try to browse HDD1 instead of HDD0.