How to clone a VirtualBox disk

How-To: Clone or Copy a VirtualBox Virtual Disk

For me, I wanted to convert a .vhd to .vdi, so I did the following:

1. Created a copy of the .vhd (I'm paranoid).
2. Changed the UUID of the copy:

   VBoxManage internalcommands sethduuid mycopy.vhd

3. Cloned the copy into .vdi format:

   VBoxManage clonehd mycopy.vhd mycopy.vdi --format VDI