How to do scheduled Windows 7 Backup on two drives/alternating days?

I created a backup on an external HDD and copied it to another identical drive.
Both drives are named the same and both get given the same drive letter (G).

The intention is to swap drives before powering up each day, and let it do a scheduled backup.
However, Windows backup recognizes that they are different drives and won't do a scheduled backup.
I can do a manual backup by selecting "Change Settings".

Is there a way to persuade Windows Backup to automatically use whichever drive is present?
If Windows Backup won't do this, is there another incremental backup program that will?
Is it something to do with the MediaID.bin file in the root directory of each drive?
Each drive has the same MediaID.bin

All advice appreciated. Thanks.

Thanks, but having spent far more time that I'd anticipated on setting up Win 7 Backup, I'd appreciate knowing that I'm going to reach my destination before I set out all over again. Getting the Win. 7 Backup to accept whichever drive is plugged in is my favoured option.

I found this article, how to configure a backup schedule for multiple disks, may helps
Configure a Backup Schedule for Multiple Storage Disks

Taplice said:

I found this article, how to configure a backup schedule for multiple disks, may helps
Configure a Backup Schedule for Multiple Storage Disks

Thanks for trying but this article is for Windows server backups ... As it says at the top:
Applies To: Windows Server 2008 R2, Windows Server 2012"