I am having the exact same problem as in this thread:
http://community.wd.com/t5/Desktop-Mobile-Drives/Do-nt-buy-a-WD-Black-Dual-Drive/m-p/740960
I am 100% certain that the space I am trying to clone is less than the 120GB SSD. In fact, I made my C: partition less than 100GB and excluded all other drives. Is there any troubleshooting that I can do? I am at the point where I am planning on installing a new OS instead of using the cloning software.