This means Johnson, who stars as riverboat captain Frank, is currently getting paid more than twice as much as Blunt, who plays scientist Lily Houghton.
The Independent has contacted The Walt Disney Company for more information.
Jungle Cruise, which is scheduled to be released in July 2020, is based on Disney's attraction of the same name, which is featured in several of its theme parks.
The movie previously attracted criticism for casting comedian Jack Whitehall as a gay character.
Jungle Cruise, which will include a coming out scene, marks the second time that an openly gay character will appear in a Disney movie, following Josh Gad's Le Fou in the 2017 live-action remake of Beauty and the Beast.
Johnson and Blunt have both scored high-profile roles recently. Johnson was ranked in fifth position in Forbes's ranking of the 100 highest paid celebrities of 2018, with reported earnings of $124m.
Part of his paycheck came from profits from the 2017 Jumanji: Welcome to the Jungle. Johnson has also starred in Moana, The Fate of the Furious, and Baywatch in recent years.
Blunt, meanwhile, currently holds the title role in Mary Poppins Returns. She has previously won a BAFTA Award and a Golden Globe. The past few years have seen her star in A Quiet Place, The Girl on the Train, and Sicario.
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