Yesterday I put two installs of Windows 7 home. Actually, not two copies. In installed one copy, And then installed another copy. I have two licenses and two different versions of Windows 7 home.
Windows did a multi boot install fro the second one. The boot menu
says:
windows 7
windows 7
Later I validated the second install. After that, I did Windows 10 as an upgrade to Windows 7. The installer found the right one and installed Windows 10. I now have both Windows 7 and the new Windows 10 on the boot menu.
But I have not yet tried to instill Windows 7 from just one CD and one COA and try multi boot. If multi-boot does harm to Microsoft, why have they not said something more explicit? And how would it harm them?