When installing Windows on a Hard Drive, and you have more than one, it's always better to unplug the one that Windows isn't on.
That way if there is an error it won't affect the other drive, and you will be sure which drive you are working on.
Also, you will know what drive the boot sector is on for sure.
Once you have Windows installed booting and working normally, then plug the other drive back in, it should appear in File Manager and work normally.
I always do this when installing new Windows on a computer with multiple drives. You only have to unplug the power cord, and afterward you just have to plug the power cord back in where you removed it from.
It only takes a few minutes, and it's worth knowing that you can't get the drives mixed up.
If you don't know which drive is which, unplug one and try and reboot, if it won't, that's the one that has the OS on it.