“X-MEN: Dark Phoenix,” to open in Chinese cinemas June 6, has undergone lengthy reshoots to change the film’s ending after it was discovered that it bore a striking resemblance to another superhero film that was also in production, Yahoo reported.

The latest “X-Men” film originally wrapped production in October 2017 and was extensively retooled during reshoots over a year later in August-September 2018, pushing the film’s release date back first from March 2018 to February 2019, then later to June this year.

The official line from everyone around the shoot is that the film’s ending — originally set in space — was changed to an earthbound sequence to give the finale a more grounded feel.

However, James McAvoy, who plays a conflicted Charles Xavier in “Dark Phoenix,” said there’s more to it than that. Talking about the reshoots, he said: “The end changed a hell of a lot. The finale had to change. There was a lot of overlap and parallels with another superhero movie.”

“They had spies on set,” said co-star Michael Fassbender, returning for a fourth time as Erik “Magneto” Lensherr, “and they basically stole our ideas.”

“We were basically trawling through the source material it seems,” said McAvoy.

The duo wouldn’t be drawn on which rival superhero movie they were referring to, leaving it wide open to speculation.

Looking at the release schedule from 2017 to now, there have been 11 major live-action DC or Marvel superhero movies in cinemas during that period. Of those films, only “Thor: Ragnarok,” “Avengers: Infinity War,” “Captain Marvel” and “Avengers: Endgame” have had lengthy space-set sequences that could potentially clash with “Dark Phoenix.” Interestingly, Disney’s acquisition of Fox — the studio behind “Dark Phoenix” — was first reported in November 2017, during the post-production phase on the new “X-Men” film.

The planned merger might have led to a “show and tell” meeting, with execs at the two rival superhero studios at Fox and Disney (Marvel Studios) looking over each other’s upcoming slates to ensure there were no clashes between their films. But which Marvel Studios film specifically might have been trawling through the same source material?

Simon Kinberg, director of “Dark Phoenix,” previously stated they’d also changed the VFX around Jean Grey’s (Sophie Turner) transformation into “Dark Phoenix” to make it more “cosmic” and less “flamy.”(SD-Agencies)