i have an WD My book Duo 2x4 TB harddisk wich has an internal RAID controller wich makes 1 disk from 2 (RAID 1– the second disk is a copy of the first one) Connected to a computer your computer sees one drive of 4TB. This disk already contains a lot of my photo file's (almost 3 TB) Can i use this disk with my LIMA ultra? Without erasing it first? This is my main backup.