How to get rid of duplicate photo album on my iphone 3gs?

So as of now I have a total of three albums in my phone. Camera Roll, Photo Library, and Wallpaper, two of them are total duplicates (Photo Library and Wallpaper). I synced 80 pictures from my desktop to my phone under the name Wallpaper but it turns out that when I did, two new albums show up resulting 80 of the same photos in both Photo Library and Wallpaper. I want to get rid of one of the duplicates… I don't care which one but one of them MUST go! My phone is running out of space and this duplicate folder is driving me crazy! I tried deleting the folder from my phone but it didn't work. When i go into my albums, I'd hit Edit on the top right hand corner and there's no little red minus sign for me to delete either one of the duplicates.

If there's no minus sign, then all I can think of is using a duplicate file finder. Connect your iPhone to your PC or Mac (whatever you are using), let your computer assign your iPhone a drive letter, and run a duplicate finder. I use Easy Duplicate Finder, but there are also other programs.