It might seem like they've made dozens of movies together.

But James and Dave Franco are only now working on their first film - and it is going to be terrible.

The brothers were both spotted on Wednesday on the Hollywood set of The Disaster Artist, a film about the making of The Room - the so-called 'worst film ever made'.

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Sibling rivalry: James and Dave Franco donned wigs on set of their first ever film together The Disaster Artist, about the 'worst movie ever made'

James plays the film's mysterious producer, writer, star and - although this last part is disputed - director Tommy Wiseau.

And he certaily looked the part, wearing heavy cargo pants, T-shirt and patterend waistcoat, with a long, scraggly black wig.

His little brother Dave meanwhile plays actor Greg Sestero, who ended up writing the behind-the-scenes book on the disastrous production on which the film is based.

Looks the part: James plays the film's mysterious producer, writer, star and - although this last part is disputed - director Tommy Wiseau

Film of a film: The film is based on the book of the same name, which tells the story of the making of The Room

Mystery: No one is entirely sure where the actor, director, producer and screenwriter- seen here at the premiere of his film Samurai Cop 2 - is from, or even what age he is

The 30-year-old was barely recogniseable in a centre-parted dirty blond wig of his own, with a beard and moustach to match.

Besides Dave's tiny background part as 'Telephone Tree #5' in 2008 drama Milk, in which James starred as Sean Penn's lover, the Franco boys have never appeared on screen together.

Since it's release in 2003, The Room has garnered a cult following. Famously described by Entertainment Weekly as 'The Citizen Kane of bad movies' it features numerous continuity errors, randomly introduced characters and subplots that are suddenly introduced and just as suddenly abandoned.

Little bro: Dave plays actor Greg Sestero, who wrote the behind-the-scenes book on the disastrous production on which the film is based

More wigs: The 30-year-old was barely recogniseable in a centre-parted dirty blond wig of his own, with a beard and moustach to match

Source material: Sestero's book The Disaster Artist details the making of what has been described as 'The Citizen Kane of bad movies'

The Disaster Artist also stars Seth Rogen as Sandy Schklair, who claims to be the original film's director.

Schklair was initially hired as a script supervisor, but ended up 'directing the entire movie'.

Speaking to MailOnline on Wednesday night, he expressed concern at how he was going to be portrayed in the film, as Rogen had completely snubbed him.

Dispute: The film also stars Seth Rogen as Sandy Schklair, who claims to be the original film's director

Winging it: Schklair - who was originally hired as a script supervisor, but told MailOnline he ended up 'directing the entire movie' - said Rogen has refused to meet him, despite playing him

He said he offered to meet Rogen to give him background on the project, and had been in touch with him via 'a couple of emails' before contact 'dried up completely'.

'If they are making a movie that features me, that is going to be seen on millions of screens around the world... don't you think they should talk to me?' he asked.

'Everyone knew we were making a stupid, funny movie,' he added. 'Everyone except Tommy, who thought he was making Gone With The Wind.'

Classic: Since it's release in 2003, The Room has garnered a cult following

Pivotal football: It features numerous continuity errors, randomly introduced characters and subplots that are suddenly introduced and just as suddenly abandoned