Could you please check the correction of your first sentence? I included a few more sentences on Stevenson's novel. Could you please have a look at them? Thank you.

1 a) 1984 can be considered as anti-utopian novel.
1)The single dominant theme in Dr Jekyll and Mr Hyde is that of the double, the divided nature of man and that things are not always what they appear.
2)Stevenson was preoccupied with this theme throughout his life and it appears in several of his works.
3)It is, however, worth remembering that the author, through Jekyll, does not argue that there are only two personalities within man but that there may be many and that the evil part may only account for a small proportion.
4) The theme of the double is expressed mainly through the characters. Obviously, Hyde represents the well-respected Jekyll’s evil nature.
5)Utterson has many subtle contradictions in his character and his friendship with his kinsman (relative) Richard Enfield seems to flourish because he is the complete opposite to him in many ways.

1 a) 1984 can be considered an anti-utopian novel.

[Title of a book needs to be in italics. Same for Dr Jekyll and Mr Hyde.]

2 - comma after "life"

3 - commas after "within man" and "many"

5 - comma after "character" - "opposite of him" (not "to")

1) The single dominant theme in Dr Jekyll and Mr Hyde is that of the duality of man and the idea that things are not always as they seem.

2) Stevenson was deeply interested in this theme and explored it in several of his works.
3) It's important to note that the author, through the character of Jekyll, doesn't argue that there are only two personalities within a person, but rather that there may be multiple facets and that the evil part might only represent a small portion.
4) The theme of duality is primarily expressed through the characters, with Hyde symbolizing the darker side of the respected Jekyll.
5) Utterson, on the other hand, exhibits various contradictions in his personality, and his friendship with his relative Richard Enfield seems to thrive because they are complete opposites in many ways.