My camera/macbook makes two copies of every photo?

I have a Nikon D90 which I use quite often, this has only just recently happened but when I upload my photos onto my macbook via iPhoto, it uploads two versions of every photo, one of a slightly light Hue, and one darker, I have tried turning this off, and looking in the handbook, but nothing. Any suggestions because its a pain when I upload them, and takes twice as long!

Do you have your camera set to save Raw+jpeg? That will create two files. Check your manual to see how you set your resolution mode. It is recommended that you keep it on the highest resolution jpeg because you can always scale down, but you can never scale up a low resolution image.