At a glance, they had it all going for them — fast cars, a successful business, toned bodies and a seemingly inseparable bond.

But the glitzy facade of yoga twins Alexandria and Anastasia Duval was already showing deep cracks a decade before the 2016 hair-pulling fight that ended in tragedy when Alexandria drove her SUV off a 200-foot Hawaiian cliff in 2016, allegedly murdering her sister in the process.

Alexandria’s lawyers in the case — which stretched into a third day of testimony Wednesday in a Hawaii court— claim the crash was an accident, but prosecutors charging her with second-degree murder say she intended to hurt or kill her sister.

Bizarre new details about their sibling rivalry emerged Tuesday as Anastasia’s former boyfriend testified that Alexandria dressed in the dead woman’s clothes and tried to seduce him after the wreck.

“She put on Anastasia’s clothes,” Federico Bailey told the court. “I started talking to her about what happened; she avoided answering any of my questions.

“When I saw her in Anastasia’s dress, it was disturbing.”

It was a startling detail considering the twins’ apparently close relationship — they lived and worked together, even moving across the United States several times over the last two decades.

But former friends and clients describe the pair as shady lushes whose juvenile tempers flared at the drop of a hat and whose toxic animus was often aimed at one another.

One 2001 incident eerily presaged the Hawaii crash, Anastasia’s former boyfriend Keith Weiss told The Palm Beach Post last year. Weiss was zipping at 85 mph down the Sawgrass Expressway along the Florida Everglades with Alexandria and Anastasia — who at the time went by their birth names Alison and Ann Dadow — in his Pontiac Sunfire when the twins erupted in a “temper tantrum” because he wouldn’t pull over so they could have another glass of wine.

Anastasia, in the front passenger seat, kicked the steering wheel, while Alexandria was screaming in the back seat, Weiss told the newspaper.

“They were like little kids throwing a temper tantrum,” he told the outlet. “I almost went off the road. I said, ‘Are you kidding me? You guys are going to wind up killing all of us.’

“They were great people when they were sober, but the minute they [started] drinking, they were like Jekyll and Hyde.’’

The sisters would later go on to found a popular South Florida fitness business, Twin Power Yoga, where they were well-liked and respected — but notorious, according to a friend.

“They were fantastic teachers, beautiful women, but I also know they were very competitive and very strong-willed,” physical trainer Victor Ayala told The Palm Beach Post.

“They seemed to have a lot of dark demons.”

Instructor Shelly Slatkin, who trained with the twins in Florida, recalled a 2013 incident where they appeared drunk as they barged into her class.

“They both came in [wearing] street clothes and changed my music and started adjusting students’ poses, the kind of things they taught me not to do,” she said. “Only afterward did I realize it may have been alcohol-induced.”

As their clientele and local celebrity grew, the twins saw an opportunity to capitalize on their fractious relationship, pitching reality-TV producers on their volatile mix of love and hate.

“We fight on a daily basis but can make up in the snap of a finger. One of us will WIN this contest because we are both SURVIVORS,’’ the women wrote in 2013.

They lived fast, driving matching Porsche Boxsters — one with the vanity plate “TWN Yoga” — and dropping dough at swanky shops along Worth Avenue in Palm Beach, but they were also living beyond their means.

In 2014, they suddenly decamped from South Florida for Park City, Utah, leaving a pile of debt and a pool of bad blood behind them.

Clients who prepaid for memberships to Twin Power Yoga never got refunds after its two locations suddenly shuttered, and an instructor who worked for the sisters said local yogis reviled them for overcharging on yoga-certification courses.

“They weren’t all rainbows and butterflies,’’ one person who trained with them told The Palm Beach Post.

“In the end, they left a really bad taste in the yoga community.”

They tried to start anew in Utah, changing their names and opening a yoga studio. But their demons followed them.

“Park City’s a really small town and once you Googled [the twins] . . . you could see what happened in Florida . . . We all kind of stayed away from them,” said Trudee Sanbonmatsu, who owns Yoga Kula Project there.

The twins filed for bankruptcy in 2014, owing more than $100,000, according to court filings. The wild sisters garnered a lengthy rap sheet in their short time in Utah, including arrests for public intoxication, fleeing the scene of an accident, DUI and assault on a police officer.

In one instance, the twins were found, their car in a ditch, arguing and pulling at each other’s hair after they’d been booted from a restaurant for getting loaded there.

Months later, Alison was arrested for DUI while Ann was collared for interfering with police and disorderly conduct. Ann “became belligerent” and threatened to kill the arresting officer as he took her to jail.

Their downward slide continued when they relocated to Maui, Hawaii, in December 2015.

At one point, Ann showed up at a homeless shelter and, using a false name, tried to shake down the operators for cash.

“She wanted us to help her out with cash . . . but we’re a shelter, we don’t give out money… I had a feeling she wasn’t really telling the truth,” shelter volunteer Kahili Moniz told Gossip Extra.

In reality, the twins were staying at the posh Westin Maui Resort and Spa.

They were cited for disorderly conduct on Christmas Eve that year, and a court issued warrants after they skipped a hearing.

Their bickering came to a deadly head in May 2016, when Alexandria crashed a camping trip that Anastasia was taking with boyfriend Bailey.

The sisters started squabbling and drove off in their Ford Explorer while Bailey was in a restroom, he testified Tuesday.

Several witnesses said they saw the twins quarreling just before the Explorer went barreling over a cliff on scenic Hana Highway.

Accident-reconstruction experts for the defense are seeking to prove the SUV plowed into a berm that forced the steering wheel to make a hard left and sent the vehicle flying off a cliff.

Alexandria has waived her right to a jury trial and her right to testify, but Judge Peter T. Cahill said Wednesday he would give her another chance to tell her side before he renders his verdict.

With wires