iPhone 4 duplicate photos

The iPhone's HDR feature essentially takes three different exposures that use different exposure settings and then combines them automatically for and HDR image. There will be an underexposure, a regular exposure, and an overexposure taken with the iPhone's camera, they will then be combined into the final HDR image. If you have selected the iPhone's HDR to the On setting then it will automatically do this, and then place the regular exposure and the iPhone's HDR image into your Photo Album.

When you are taking HDR photos with the iPhone you are going to notice that the default setting is to save both the original base photos as well as the HDR photo that is created. This can be turned off easily in the standard iPhone Photo settings, where you can find in the iPhone Settings right above Store and below iPod. There you can turn the "Keep Normal Photo" button to the Off position, which will stop the saving of both the standard exposure and the HDR photo.