It looks like the drivers may have been "mixed up" with the drives. Try rebooting, then plug only the 4TB drive in and see if everything is there. If not, try reinstalling the drivers for it.
Next, I would try to transfer the data from another machine using a share across the network.
but i tried plugging in the 1tb portable hard drive to a computer that the 4tb hasnt been plugged into yet and it gives the same result.