[tlug] Program to Mirror Individual Files?

[CL <az.4tlug@example.com>]

Question:  Does anyone know of a program that can be run from CD, DVD, 
USB drive that permits the mirroring of individual files, rather than 
partitions or whole disks?  I am trying to copy three VirtualBox .vdi 
disks between HDDs without the rest of the contents of the original HDD, 
which is my "old" Kubuntu 13.10 installation. Copying between disks as 
Root seems to corrupt the .vdi files.  I have not yet tried importing 
the three VBox installations, though. If others have transferred VBoxes 
between HDDs, I'd like to hear what worked for you.

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CL