I just dl'ed the pack, loaded up the game ... and I have two copies of Moonwood Mill in my game, and two copies of all the MWM NPCs in my families. I modified the starter home in the first instance...
Repairing the game (twice) did not fix it for me, but it was a new file, so I deleted it. My regular save has just one. I would have liked to have 2, but I knew that would be unstable.