I've been modding in Castle Knightstone from Centurion, I like all his work and use some if his castles but Knightstone seemed a bit inferior to his other works so I started adding some extra furniture and clutter. Everything went fine up until recently, I started adding some filled bookshelves with books I made static in Nifskope from the Bookjackets mod and some from Meo's Booksets. Right when I was almost done I got an error about duplicate entries. Now I've figured out this error occurs when objects get the same FormID for some reason. I reloaded a backup and went from there just saving more often and reloading more often and I managed to finish the bookshelves, while getting a few more of those errors along the way. Yesterday I was in the final stages of adding clutter, I added some flora and pots and it happened again. Here's the error message I got: I added 1 manabloom and 1 ceramic bowl, and they got a FormID that two books were already using. I didn't alter these books I haven't touched anything except adding these two items. I just can't figure out why this happens but it is really aggravating when you have to redo stuff all the time. Am I making some giant noob mistake which causes this to happen all the time or is this some strange quirk of the CS? And is there a way to prevent this? I know it can be fixed with TES4Edit just not exactly how yet, but I would preferably like to prevent this from happening altogether. Any help and tips would be really appreciated.