I have just upgraded windows 7 to windows 10...
I've bought a new ssd to install windows 10, but it was installed over my windows 7(in the old ssd) in the process....

Articles in this forum say that you cannot dual boot windows 7 and windows 10, since once you proceed to upgrade, windows 7 key is no longer valid....

If i roll back to windows 7, and install windows 10 using usb in a new ssd that i have just bought, will dual booting work?

And another question... Can i install two windows 10 system on seperate drive in the same computer?