Computer importing duplicate photos from camera?

I have the nikon d5000 and i use this thing where i insert my sd card and connect the usb to the computer and i use iphoto to import my photos. I don't know weather its my camera my sd card importing device or iphoto duplicating the photos but its really annoying… It looks like its going to import what i selected but when i go to the photots there's a duplicate of every photo but its weird… The duplicate photo is changed somehow like less saturation and more glowy its like it imports a new set of automatic adjusted photos… I've also used image capture to import my photo and it does the same thing!
abyone know how to stop this and what's making this happen?

Could it be that your old images are still on your card?

When was the last time you formatted the memory card using the format feature on your D5000?

This should be done after each successful copying of your image files to your computer.

Maybe what you're seeing is the photo and its thumbnail. Most photo apps create a thumbnail of the pic so that it can quickly display a small version of the pic. Just ignore them.