When i upload my pictures from my nikon d5000, they come out as duplicates?

Every single time i've connected my nikon d5000 to my computer, the pictures show up, but two pop up.one is of good quality, the other is darker. It's really annoying having to sift through the pictures and find the good ones and delete the bad ones, when i only take one picture in the first place.

Your camera is set to RAW+JPEG, meaning it is saving both the RAW image, and a JPEG copy of the RAW image.

Your manual will tell you how to change the setting so that the camera only saves one or the other.