A few days ago in Dublin, an actor lost his job. That might not count as major news, but for the operation in question it represented a 50 per cent reduction in its floor staff. Another industry might call this “downsizing”. Here, though, a two-hander show had simply been “reimagined” as a solo run.

The play is Mark O'Rowe's Howie the Rookie , two successive monologues written for two actors. In Landmark's forthcoming staging, both parts will be played by Tom Vaughan Lawlor , whose performance as a gangster in the Abbey 's The Resistible Rise of Arturo Ui proved him one of the most extraordinary of his generation, and whose performance as a gangster in RTÉ 's Love/Hate also made him one of the most recognisable. Who wouldn't want to see more of him?

Certainly not O’Rowe, who is directing Vaughan Lawlor in the new production, raising all kinds of questions about his original intentions.

Set in a Dublin underworld heaving with borrowed mythologies, the story has a yin and yang of apparent divisions and unlikely unions. The Howie Lee and The Rookie Lee begin as enemies and, more pointedly, as opposites. Howie is the fighter, Rookie the lover. Giving both parts to the same performer is a challenge in versatility, but it suggests something deeper – that one person is slashed in two: Howie/Rookie.

That might put the production in a long line of theatrical split personalities. One of Waiting for Godot 's tramps is defined by his intellect, the other by his senses; Tom Stoppard 's versions of Rosencrantz and Guildenstern are almost indistinguishable, and imaginative casting can complicate famous double acts.

When, in 2000, Philip Seymour Hoffman and John C Reilly alternated the roles of an uptight screenwriter and his menacing brother in True West , it teased audiences with an unsettling duality, just as Benedict Cumberbatch and Jonny Lee Miller 's recent switching between Frankenstein and the Creature presented two sides of the same monster.

Turning Howie the Rookie into a solo show reverses the equation, and it chimes with another stage phenomenon: virtuoso displays of isolation. Alan Cumming is now performing a one-man version of Macbeth on Broadway, played as a delusion in a psychiatric hospital. In Dublin you can see John Hurt performing opposite recordings of himself in Krapp's Last Tape, essentially portraying different versions of the same man.

This is where an actor’s resumé has something in common with the mysteries of human psychology: we all contain multitudes. The theatre’s fascination with splitting people up and getting them back together subtly taps into this.

However O'Rowe and Vaughan Lawlor are reimagining Howie the Rookie, one paradox will be intriguing. Originally the embattled protagonists had an unlikely person to turn to. Now they have somebody they have to turn in to.