A. Warren Oddson (the artist/timeline solver)from The World of Dark Shadows had a theory this return to 1796 was a trap set by Angelique to lure Vicky,
Peter, Ben, and Barnabas into a fantasy 1796 to do away with Vicky once and for all.
When Barnabas has Ben torch her, Vicky and Peter were able to escape the trap, but Barnabas had to find a way out, which was his chained coffin. Nathan and Natalie were a "fail safe" device in case something
went wrong. When ben took care of that and chained Barnabas in the coffin, both returned to where they belonged.
Thus, 1795 was never really changed.
How does this sound to you?