I'll also use my clone duplicator to clone both drives to a couple new WD green 2TB drives and then retire these as backups.
Want to think about that one? You're taking a known unstable drive and you want to use it as a backup? So that way when the active drive dies you have a lower probability of having a viable backup?
I commend you for wanting to do backups, but unless you're using it for a real short rotation then I'd just overwrite the drive with 0s and toss it.