1) The Landon Carter born ~1760 was married to Elizabeth MacLin.This is the Landon Carter who was the son of John Carter of Watauga (Carter County, Tennessee).
2)The Landon J. Carter who was born ~1800 and was married to Mary Wilson *may* have been a son of John (Jr.) Carter & wife Catherine Blevins.That is, Landon J. Carter would have been a nephew of the above Landon Carter.
3)Landon & Elizabeth MacLin had a son Alfred Moore Carter who had a son named Landon D. Carter who was born ~1815.
There has been speculation that John Carter of Watauga was related to Robert "King" Carter but the details of that relationship are not known.Robert "King" Carter and his second wife Elizabeth Landon had a son named Landon Carter who was married three times.
There were several other Landon Carter's around but I haven't gotten into all of them.