I had not heard of the Hatteras Island theory. I thought the most commonly accepted theory was that they left for Croatoan Island (the word Croatoan was carved on a tree trunk on Roanoke Island).
Yes, they may have split into separate groups, one set going with the Indians and one to Hatteras Island.
There were no signs of the colonists having planted crops or even clearing any ground for farming. So they may have decided that life was too difficult in the New World and one group wanted to return to England, while the other group wanted to stay with the Indians.............