It was supposed to be a one-season-and-done creative workout for two longtime Aussie friends. But success got in the way, and now the legal drama series “Rake” has become a transcontinental franchise.

In the coming weeks, “Rake” co-creator/exec producer Peter Duncan is going to have the oh-so-global experience of having two renditions of the series in production at the same time.

The Australian original, featuring Richard Roxburgh as a crafty criminal defense attorney living on the edge with a messy personal life, is heading into its third season on Oz’s ABC.

Fox earlier this month greenlit an American spin on the format from Sony Pictures TV, toplined by Greg Kinnear.

Even more unusual is the fact that Duncan is now in the U.S. co-piloting the ship for the Fox series with veteran showrunner Peter Tolan. The major U.S. networks have been eagerly scooping up foreign series for adaptations in recent years, but in most cases the creators get little more than a check and an exec producer credit. Duncan credits Sony TV brass and his reps at CAA for recognizing that he needed to steer the new version if they wanted to retain the flair that made the show stand out in the first place (the Oz series had exposure on DirecTV’s Audience Network channel).

“Sony said, if we’re going to do it, you’re going to come on the journey with us and lead us,” Duncan says. “The show is not a widget. There are bits of this show that I know better than anyone. We all thought it was in the show’s best interest that I be there to make sure we captured that certain tone and the dramatic essence.”

Initially, Duncan was paired with Paul Attanasio on the Sony TV adaptation, but “for one reason or another it didn’t work out,” Duncan says, noting that Attanasio got busy writing another feature project. Tolan, late of FX’s “Rescue Me,” proved to be a good fit with Duncan’s sensibilities, and they collaborated on numerous drafts of the pilot script that eventually impressed Fox.

“A lot of (Tolan’s contribution) was the Americanization of it, which is great because he’s so clever and so funny,” Duncan says. “Despite the fact that I grew up on American television, I’m not an American, so the vernacular is not there for me. I write what I think is a good pass, and then it goes into the Tolan machine and comes out making sense to the American public.”

Before “Rake,” Duncan’s showbiz experience was largely as a writer-director in Australia’s indie film sector, after he gave up his career in law. He and Roxburgh developed the “Rake” concept in a series of “latenight conversations,” he says.

“Richard had a desire to play a brilliant but broken character,” Duncan says. The world of criminal defense law stood out because “a criminal barrister can enter any strata of society, from the most evil to the most benign.”

With the pedigree of Duncan and Roxburgh, “Rake” was an easy sell to the ABC at a time when Oz’s state broadcaster “wanted to get a bit edgier,” Duncan says. But the duo still thought it would be limited to a single season of eight episodes, which bowed in 2010. “Rake” began pulling in awards and a steadily growing aud. Its third season of eight episodes is targeted to bow in Australia in February, which could be around the time the U.S. version bows on Fox (the network has yet to specify a timeslot beyond midseason).

Duncan has penned a few scripts for the new batch of Australian episodes. But for the most part he’s focused on launching the U.S. series, including the unfamiliar process of interviewing writers to assemble a staff of a half-dozen or so scribes. In Australia, the writing is handled by three people, Duncan, Roxburgh and Andrew Knight.

“It’s a pretty shambolic process (in Oz) of us shouting at each other, having lunch, and the some constructive conversations and then shouting again,” Duncan says. “It all works because we’re very good friends. To be in a room with six to seven other people will be interesting.”

The Fox rendition will be “clearly rooted” in the original, but will have plenty of its own touches, Duncan says. They’d be hard-pressed to simply remake the Aussie scripts if only because the running times are so different — an average of 57 minutes in Oz vs. 42 minutes in the U.S. “We’ll have to be shrewdly selective and careful not to overstuff,” he says.

In a fatherly way, Duncan admits it will be hard to be removed from the Oz production process. He plans to see the final cuts before they hit the airwaves but is otherwise handing the reins to a trusted new showrunner.

“It would be greedy of me to try to do both because I wouldn’t be able to give either production adequate attention,” he says. “But I will be keeping an irresistibly curious eye on them, occasionally glancing at what’s going on as a caring parent ought to.”