If your running oscam then ideally you need to go into the oscam.server file and just delete the host, user name and password. Then save and restart oscam. Now when you back up your files will be free of any server details.
Obviously make sure you have a copy of any server details before deleting things.
Once you have your back up then you can place your details back into your first receiver.
Your second receiver can now be flashed and will be exactly the same, the only thing to do then is contact your server provider and ask whether the line will cover 2 twin tuners. ;-)