How to stop HDR camera mode storing "duplicate" pictures on iPhone 4

iPhone 4 users using iOS 4.1 may well be aware already of the HDR (High Dynamic Range) camera mode. HDR blends the best parts of 3 separate exposures into a single photo. In this mode, your iPhone 4 takes three photos to combine them into one HDR image (higher-quality) and saving the normal picture in your camera roll by default. So you'll get two "duplicate" pictures in the Camera Roll. Many users prefer to keep only the HDR picture to save storage space.

In case you want to just keep the HDR image (higher-quality) and automatically delete the original one, here's the how-to prevent HDR camera mode storing two pictures on iPhone 4
1. Go to "Settings"
2. Click on "Photos"
3. Slide the "Keep Normal Photo" toggle switch to "OFF"
4. Done!

Note: Sometimes iPhone 4 users want to keep both HDR and normal shots, because the non-HDR picture might be better than the HDR version, depending on many factors. If you prefer this, leave it "ON" to save the normally exposed photo in addition to the HDR picture. You can manually delete one of them later.