VirtualBox gives you to ability to create clones of your virtual machines.
Clones can help:
-When you need to share a virtual machine with several users.
-In the event that you are making a major modification to a virtual machine, you can always use the clone as a backup in case of error,
To clone a virtual machine:
Select the guest OS.
Click on the Machine menu > Clone.
Follow the onscreen instructions.
You can choose to create a:
Full clone - independent from the parent virtual machine
Linked clone - shares the same hard drive files as the parent virtual machine.