Notice in Mavericks that the icon for the time machine drive is not blue when computer is first started and takes minutes to Blue In this case in this screen shot it has.
But explain why Backup disk and available disk show the same. And if you switch to availble disk to get it turn blue. Then it starts a new Backup from Scratch.
Once a Drive is selected should that only be listed In Backup and no other times should be show other than time capsule or other drives.
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