[mothered]

From what I have read, if you run a sandbox you need a second windows key as its like another copy of windows in the sandbox, or am I maybe thinking of when its a virtual machine?. I've never ran a sandbox before as computers aren't my thing really so I could be way off

No, Sandboxie has no relevance to your Windows product key.

You're referring to a VM and because It operates In Its own Isolated environment, you'd need to active the OS.