Had the same problem from signing in with 2 IDs and fixed it.
Sign in to icloud with the ID you DON'T want to use and turn on photostream. Take a picture and wait until it uploads, then go back to the settings and turn off photostream. It will give you a warning and then it will remove the photostream folder for that account.
Then remove that account from your phone and sign in with the ID you want to use and you should have just the one photostream album.