I am a certified computer dummy and I can tell you it is never easy.
Macrium wants to put thing back the way they were.
I have multiple installs, but each install has its own livens or permission. In general, Microsoft does not promote multiple instals
of the same license. I own three COAs of Windows 7. So I can have Windows 7 on one machine plus one Windows 10 on another.
However, at the moment, one can still use the Windows 10 Technical Preview, which has a license to use for evaluation for a period of tome. So I also have the Win Ten TR on a machine.
In short, you need a COA for each install with the exception of repair or evaluation.
EDIT: Check this link from Microsoft. It explains how to do a dual boot.
http://windows.microsoft.com/en-us/windows/install-multiple-operating-system-multiboot#1TC=windows-7If your computer's hard disk has adequate free disk space, you can install a newer version of Windows on a separate partition and keep the earlier version of Windows on your computer. This is called a multiboot or dual-boot configuration. Whenever you start your computer, you can then choose which version of Windows to run. For more information...
Warning
You must install the older operating system first, and then install the more recent operating system. If you don't (for example, if you install Windows Vista on a computer already running Windows 7), you can render your system inoperable. This can happen because earlier versions of Windows don't recognize the startup files used in more recent versions of Windows and can overwrite them.
