First off, I can only assume that you meant that you have 67.8 Mb left on your drive before the move, and that after the move your computer showed the same amount of available space. What was the exact method of moving the file? What platform/OS do you run? Is the directory protected in any way? Any any of these drives networked drives?
There are myriad reasons for this, but your particular answer can only be fleshed out with more detail.