How do I get rid of double pictures on my Iphone 4

The reason for the pointer is as I provided.

This way you can view the photos in an album only by selecting the album, or view all photos transferred from your computer by selecting Photo Library.

The pointer allows for not having to duplicate the photos as in taking double the storage space aloing with all photos transferred from your computer being stored in one location.

The same applies to music. Music in a playlist is not duplicated as in taking double the storage space. This way you can play the music in a playlist only by selecting the playlist, or you can select from all songs in your library on the computer, iPod, or iOS device.

They are not duplicates & no, you can't delete the Photo Library. iPhone stores photos the same way that iPhoto does on a Mac. All synced photos are stored in the Photo Library. The various albums/folders merely contain pointers to the actual photos in your Photo Library, not duplicates.

All photos transferred from your computer via the iTunes sync/transfer process are stored in the iPhone's Photo Library. All photos in albums, events, etc. below Photo Library are not duplicated as in taking double the storage space. The photos in the albums below include a pointer only to the original photos stored in the Photo Library. This way you can view the photos in an album only by selecting the album, or view all photos transferred from your computer by selecting Photo Library.

The same applies to iTunes music placed in playlists. The music in playlists is not duplicated as in taking double the storage space. Music in playlists includes a pointer only to the original music stored in the main music library.

You need to delete them manually

To stop this in the future, go into the camera app and make sure you don't have "HDR" turned on.

Double photos where - in the Camera Roll?

Why do you think you have duplicates?

Are you talking about the Photo Library?

Please explain

There are no duplicates do delete.