i recently switched from an iphone 4 to a 4S. The new 4S was able to become a mirror image of the 4 thanks to iCloud, however, my iCloud now recognizes BOTH of the phones, and will not let me back up my 4S. How do i make it only recognize the 4s?

When you say that it recognizes both phones are you sure you aren't just seeing both backups? iCloud should back up your new phone if you have iCloud Backup turned to On in Settings>iCloud>Storage & Backup. But you may still have the old backup stored in your account as well when you check in Settings>iCloud>Storage & Backup>Manage Storage on the Backups list. If you no longer need the backup of your old phone, tap it and then tap Delete Backup.