The title emerges from the claim that 3000 trees were planted in memory of anti-nuclear campaigner MacRae, who was found dying in his car on a remote Highland road with a single gunshot wound to his head, apparently fired from his own gun.
Yet the gun had been fired twice, and former policeman Donald Morrison claimed he saw MacRae's car drive off from Glasgow on the fateful day, followed by Special Branch officers.
There are many unanswered questions about the death of MacRae, prompting speculation he was murdered by the state, but why would two plays appear based on MacRae's story, 19 years after his death? Actor, writer, musician and former journalist Andy Paterson explains his version.
"I was aware of Willie's death from my own family who had been steeped in SNP activism since I was young, and then a magazine story highlighted the story about 10 years ago," he says. "But it wasn't until I decided to study at the Royal Conservatoire in 2011 the Willie MacRae story came back into my head. My research project was on biographical theatre and I came up with a piece about Willie, to be produced at the Arches Theatre."
The half-hour performance prompted Paterson to develop his monologue, featuring music by Edinburgh band, Oi Polloi, in which he appears as MacRae, from the grave, speculating on the events leading up to his death.
Writer George Gunn had meantime completed his own 3000 Trees play and approached River City actor Adam Robertson with a view to staging it. Robertson in turn involved producer Mark MacNicol, who believed the play could be an Edinburgh Festival success.
George Gunn's 3000 Trees takes a very different approach to the Willie MacRae story. Gunn's script sees MacRae transformed into the fictional character Willie MacKay, and tells of the last hour in the central character's life.
Billy Riddoch plays the lead role, Helen Mackay is the daughter of MacKay's best friend and Adam Robertson is a Special Branch officer.
What both plays have in common is a passionate involvement in the subject. Paterson's research involved speaking to political luminaries such as Margo MacDonald. "Margo believed Willie hadn't killed himself, yet Gordon Wilson, who is also a lawyer, dismissed the notion."
"It was suggested Willie MacRae was involved in the Scottish National Liberation Army in the Seventies but it's hard to unpick the truth of all this. Willie also seemed to have a finger in so many pies, looking into the importation of drugs into the north-west Highlands.
"The death in itself is bizarre, to say the least. It was claimed to be suicide, but why would a lawyer carry a handgun around with him? Was he fearful for his own life? Why was the gun found some distance from the car?
"Then there's the policeman Donald Morrison who saw Willie outside an off-licence in Glasgow, as he was about to drive off to his holiday cottage."
Paterson adds: "Senior figures in the SNP were under surveillance in the Seventies. Margo was very clear about that.
"Others have said Willie, who was gay, had had a troubled relationship. And why would a man who is planning to kill himself buy provisions to last him the weekend at his holiday cottage?"
Mark MacNicol has similar questions.
"There's the speed the investigation [into his death] was closed down after his body was found. The beat policeman saw MacRae had bought two bottles of Islay Mist whisky, the only brand he drank. Then when the body was found there were two whisky bottles in the car. But it wasn't Islay Mist."
Both Paterson and MacNicol were initially dismayed to hear of the other's rival production.
"I was amazed the story had never been dramatised for theatre," says Paterson, "and then two buses come along at the one time."
MacNicol agrees; "There is no doubt some will be confused as to what show they are buying tickets for, but hopefully it will all balance out."
The reality is the plays will complement each other, telling the same story in very different ways.
"I think that's the case," says MacNicol. "The fact we're both taking MacRae to the Festival should really convince audiences it's a story worth telling."
He adds: "And if we sell out, the first thing I'll do is try and make sure Andy's show is a sell-out too."
To add one final coincidence: when Helen Mackay began her own research she was stunned to discover the address of MacRae's home in Glasgow's Queen's Park is the flat she now lives in.
3000 Trees: The Death of Mr William MacRae starring Andy Paterson is at Sweet Grassmarket, July 31-August 24
3000 Trees: starring Adam Robertson, Helen Mackay and Billy Riddoch, is at Gryphon@WestEnd, August 1-24