Writer-director Riley Stearns picked up on something that he was able to cash in on in casting Karen Gillan in “Dual,” his dark sci-fi thriller about a future when cloned “replacements” take over for the dying. Although he had to — no doubt — be delicate in bringing it up, the Scottish Gillan’s deadpan-to-the-point-of-flat turns when she’s voicing “American” roles in Hollywood films (“Jumanji,” “Guardians of the Galaxy”) made her perfect for the dual roles in this film.

Sounding like an automata seems to come naturally to her.

That’s the way almost everyone comes off in “Dual,” whose title is both literal — a company is creating duplicates, who spend “imprinting” time with their dying”originals” — and a pun. When both versions of the same person want to carry on living, the duplicates have rights, among them the right to trial by combat. The winner gets to live the original’s life. The loser dies by the other’s hand.

Filmed in Finland, with a number of British accents in support, almost every character comes off as the way movies and TV depict “on the spectrum.” To a one, they’re blank-faced, with emotionless voices, even when given the worst possible news by the flat-British-accented doctor (June Hyde) who confirms what Sarah’s already heard from her unemotional husband (Beaulah Koale).

“You’re dying.”

Even Sarah’s controlling, martinet of a mother (Maija Paunio) seems like a clone that hasn’t learned to raise or even modulate her voice as she’s criticizing her almost-estranged daughter’s eating and everything else.

Sarah’s own social-signals awkwardness extends to “reading” her chilly husband, who keeps finding reasons to be away from home for work, his distracted, deflecting video calls home making the viewer and Sarah suspicious. Has he checked out of the marriage?

Sarah’s bizarre choice to spend all she has and much of her future earnings based on a sales pitch that ends with “You may be dying, but don’t let that affect those you love most” says more about her lack of sales resistance than her empathy. Who’d want to spare pain to those two?

Her husband taking to her clone during the “imprinting” break-in period isn’t comforting, either.

How will she, her replacement and her “loved ones” take the news that she has gone into remission, that she wants to “decommission” her clone and go back to the way things were? Not well.

And for the first almost only time in the movie, Sarah shows something like emotion herself.

“I’m gonna f—–g ABORT you!”

A few things here point to the black comedy intentions of “Dual.” One is that punned title. Another is the uniformly flat way everybody washes the emotions out of their performances. A third might be the way Aaron Paul, playing the personal combat trainer Sarah hires to get her through her mortal combat with her physical twin, pronounces “cache,” as in “cache of weapons,” as “cachet.”

Granted, personal trainers are rarely English majors with minors in French. But come on.

A running gag — if you can call it that — is the sneaking feeling that this is all some sort of bank-account emptying scam. Sarah is not just payinf a clone to carry on her life in her stead, at no benefit to herself. She’s got to hire a lawyer familiar with “duplicate” law when she “goes into remission,” and pay to support the duplicate up until the day of their televised combat. And she’s got to shell out for a trainer to teach her how to kill her replacement.

That’s some next level legal extortion.

But a couple of one-liners and a single jokey scene aside, “Dual” doesn’t play as dark comedy. Having too many characters vocalize in the same monotone may imply that the duplicates win a lot more of these duels than you think. It also makes for a film dominated by intentionally dull, emotionless and unfunny performances.

An opening “duel” starring single-scene actor Theo James has higher B-movie stakes, more emotion and more suspense than any of what follows.

It’s not the trickiest plot to decipher long before the finale. But the big hang-up for me was the chilly disconnect of it all. There is nobody to relate to. That makes the movie’s muddled message a chore to plow through and its payoff more of a shrug that the sharp slap it could have been.

Rating: R for violent content, some sexual content, language and graphic nudity

Cast: Karen Gillan, Beaulah Koale, Maija Paunio, Theo James and Aaron Paul.

Credits: Scripted and directed by Riley Stearns. An RLJE release.

Running time: 1:35