I have my D7000 set to use its second SD Card slot to back up and I am shooting in raw (NEF).
Every image is shown twice in playback mode, and when the images are imported to Photos (MacOS). This makes deleting individual images a pain.
As it is copying the images to both cards it makes some sense, but the menu says "backup" not "duplicate" so I would at least expect the internal firmware to understand and not show the images twice.
To clarify a little, when in playback/review mode, I see the images in chronological order, first for card 1 then again for card 2, so if I have taken images A, B and C I would see A1 -> B1 -> C1 -> A2 -> B2 -> B2 (1 and 2 represent the card slot). So to delete image B I have to delete two images, once for each card.
Is this normal behaviour?
Firmware is A 1.04 B 1.05 L 1.002