Actually this doesn't work!!!!
However i did find out a way in which you can transfer files across the two harddrives without using the network.
1)
Install Telnet by following this link
Removed. You know why.
2)
login using telnet by using the ip-address of your device assinged by the router or by you.
3) use cd, ls, mv functions to navigate and copy files between the drives.
cd - changes directories
ls - lists what's inside it
mv will move files from one location to another
...you can also you cp for copy
example
/mnt/HD_a2/BT/Complete # mv Smallville* /mnt/HD_b2/Movies/Smallville
this command starts after the # sign with the command "mv" for moving
and it will move all the files that start with Smallville from the bittorrent completed folder to a folder Smallvile on the second harddrive.
/mnt/HD_a2/ = Volume_1
/mnt/HD_b2/ = Volume_2
doing [command] ? will reveal the help and options for that command
This will move about 2 gig in couple of minutes...
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now lets find a way to unrar

SOLUTION!
OK, here's the deal. If you are cut/copy within the same window (of course you have to navigate up and around) you will have no problems. If you cut then copy into another window you end up copying across the network.
Cheers!