Why do I have double copies of the same photo?

I'm trying to download some photos from my Nikon D90 Camera into iPhoto. However, I seem to always have 2 copies of each photo when trying to download.

You probably have the camera set to capture RAW + jpeg.

Another possibility is you are using the "D lighting" option, which saves a copy along with the original.

You have it set to take RAW + jpeg

If you want to change your camera settings, I suggest you read the user manual that came in the box with your camera.

If you have lost it, then get it here: http://www.nikonusa.com/...D90_en.pdf

One is a RAW files (.nef for Nikon) and the other is a jpg.