I'm not sure how Ancestry lists them but there are three headings in the Enumerator's Census Books.
1. Island of ....
2. Parish or Island ....
3. Town of ....

For Douglas:-
1 = Man
2 = (Island crossed out) Braddan or (C)Onchan
3 = Douglas

The CEBs for Islands are slightly different to the mainland books.

There are two Sarah listings in Douglas, aged 5 and 3.