Lightroom :: Transferring Files To Computer (OSX - Snow Leopard) Via USB Cable

Nikon D800 + LR4 import problem with dual card system:

I am transferring files to my computer (OSX, snow leopard) via USB cable. I am using dual card system with my camera: CF and SD. I am using the "backup" option which means that the content of both memory cards is identical. NEF + NEF with identical file names.

When the camera is connected to the computer and LR4 "import" is opened, LR4 does not show "D800 1" or "D800 2" -- it shows only "D800". This means that I cannot select a card which I would like to import the files from (like I can do with D700 or D3). And most of all, LR4 reacts inconsistently on "Don't import suspected duplicates". Usually, it wants to import all images on both cards -- this means that all files would be imported twice.

At the moment, in my D800, I have SD and CF with 3 identical NEF files on both cards. "Don't import suspected duplicates" is selected. In the import window I can see that LR4 wants to import 5 files: 0474+0474 (duplicates), 0475, 0476+0476 (duplicates). So, out from 6 images it recognizes that there is a one duplicate about to be imported, but those two others are not duplicates?