Mandolin Orange plays Cat’s Cradle Saturday, Sept. 24, at 9 p.m. The Tender Fruit opens, and tickets cost $10.

Last December, Mandolin Orange, the Carrboro folk-like band of Emily Frantz and Andrew Marlin, holed up in a cabin in Franklin, N.C., a mountain town with spotty cellphone service along the sparsely inhabited fringe of the Nantahala National Forest.

As snow fell, Frantz, Marlin and a borrowed rhythm section transformed the little house into a recording studio. They tracked most of Haste Make, the intended follow-up to 2010’s well-received Quiet Little Room, and came home.

The plan was to release Haste Make in September, and that hasn’t changed. But it won’t be released alone: Haste Make and the newer Hard-Hearted Stranger share both packaging and a release date, although Frantz and Marlin agree that the two are very different, discrete albums.

“It wasn’t until this past June that we decided we were going to do the second record,” songwriter and guitarist Marlin explains. His crutches sit idly nearby; after a recent fall from the Haw River dam in Bynum, Marlin is likely to play Mandolin Orange’s upcoming release show in a wheelchair. But he refers to this accident with the same grin and insouciant shrug he uses when discussing the happy accident of the double LP.

“We had already done the band record, Haste Make, with Jeff Crawford and James Wallace,” Marlin continues, referring to their time in the cabin with the occasional rhythm section Mandolin Orange shares with several local bands. With those sessions done, he and Frantz demoed a few tunes in late spring, potentially for Haste Make‘s follow-up. But they liked the new songs too much to put them on the back burner. “We were just like, ‘Screw it. Let’s just do a double record.’”

A good thing, too: Taken together, these Mandolin Orange LPs show a band with far more range and vibrancy than the otherwise fine Quiet Little Room might have suggested. And, after all, Mandolin Orange’s success is a story of happenstance that stretches back about a decade. Marlin and Frantz met at a bluegrass jam just less than three years ago. But in 2001, Frantz began playing around Chapel Hill in what she calls a “strict bluegrass traditional band.” By odd symmetry, Marlin bought his first guitar at around the same time. They were both 14.

“I had a really narrow view of what I would be doing. I just figured it would be bluegrass forever,” says Frantz. From learning violin via the Suzuki method at an early age to adhering to a rigid Appalachian fiddler tradition as a teen, she’d never played original music. Some 70 miles to the northeast, in Warrenton, Pearl Jam’s Riot Act inspired the teenage Marlin to write songs. A friend named Hillman Poythress was one of the only other musicians around, but he was more into Pantera than Eddie Vedder’s earnest bleats. In any larger music community, the two guitarists probably wouldn’t have played together. In Warrenton, they formed an unlikely genre-splicing project.

“I would be playing acoustic songwriter stuff, and he would be playing this really crazy electric shreddy stuff around it,” Marlin says. After high school, he followed an opportunity to work at Rubber Room Studio in Chapel Hill. Poythress stayed in Warrenton, so Marlin went soloat least until he met Frantz.

The Mandolin Orange tale quickly becomes a more familiar narrative, echoing area couple bands like Birds and Arrows, the badly missed Veelee and Bowerbirds: boy meets girl; boy and girl write songs, play shows and release records; audiences approve. This weekend, in fact, they’ll headline Cat’s Cradle, one of the largest and most venerated clubs in the region.

“When I first moved here,” says Marlin of open jams he attended just four years ago, “I know I would take my instrument places and it would be like, ‘No, we’re not going to play your song.’ And now we sit in with other people who’re kind of doing the same thing we’re doing.”

On this particular sunny afternoon at Carrboro’s Open Eye Cafe, they seem to know everyone. “Getting out and getting the respect of other people,” has helped a lot, says Marlin. “And I think confidence has allowed us to take a little more risk.”

One of those risks, of course, was bringing a rhythm section into the fold of a treasured acoustic duo. Going from a pair to a full-on band could have changed the Mandolin Orange character dramatically. But Haste Make and Hard-Hearted Stranger are self-contained yet complementary records. Even with the added push of bass and drums, the duo record is more energetic than the full-band outing. Compared with the wintry Haste Make, Hard-Hearted Stranger is more immediately engaging. It’s a welcome subversion of expectations, where neither take feels like a collection of B-sides, a common weakness of double LPs.

With its doo-wop-derived electric guitar and gentle country shuffle, Haste Make‘s “Lines on the Floor” shows a band more inclined to borrow from the rock world than Quiet Little Room. Lyrically, Marlin has grown spectacularly since that record. “Like a rock rolling down the hill/ I was looking for something to kill,” he sings during “Wake Me.” On Hard-Hearted Stranger‘s stark, exceptionally eloquent “Clover Tune,” Marlin sings, “You wonder why you look all over/ just to find a four-leaf clover and as you pick it/ it just withers away.” Those levels of imagistic and emotional depth thread through both albums.

“We’ve kind of stopped trying to decide on one or the other, which is one reason we’ve done the album this way,” says Frantz of the duo-versus-quartet binary. Now, the original Mandolin Orange pair and the quartet Expandolin Orange, as Andrew puns, can exist as distinct bands without hurt feelings from the intermittent members. “We love doing things both ways.”