So both drives work? That's good news. Unfortunately, as I already mentioned, you won't be able to boot to Windows by using a drive with Windows from another computer. If you want to boot to Windows with that drive perhaps you should migrate/clone the drive you can boot to Windows with over to this drive you can't boot to Windows with. However, note that you should backup your information before you do that as the clone will erase everything on the destination drive.
The other option if you want to be able to boot to Windows by using the drive, which you can't use for booting right now, is to make a fresh install of Windows on it.
I hope that I've been able to answer your question. But please don't hesitate to ask if there's something unclear, or if I haven't understood your question.