He was formally refused bail in Dubbo Local Court in early January following the double fatal crash, which occurred on January 5, after initially being charged with a string of offences days after the incident.

On Thursday, almost two full months since the crash, police laid additional charges against the man following further inquiries.

He was charged with two counts of manslaughter and several dangerous driving offences while under the influence of drugs.

He is scheduled to reappear in the same court on Wednesday, March 10.

Initially facing 14 charges, the man's bail application was refused in Dubbo court by magistrate Therese Hamilton on January 12, he appeared via video link from Bathurst Correctional Centre.

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She said there was an unacceptable risk of him failing to appear and he had a history of unlicensed driving matters, also citing the circumstances surrounding the alleged hit-and-run as one of the reasons the accused was deemed a flight risk.

The man allegedly fled before police arrived at the scene of the incident, emergency services had been called to Warne Street in Wellington following reports five pedestrians had been struck by a car.

Police were told a 34-year-old woman and four boys - aged six, seven, nine and 10 - were walking along the grass on the side of the road when they were struck by a Holden Commodore.

They were treated by NSW Ambulance paramedics however the two younger boys - six and seven - died at the scene.

The woman was airlifted to Westmead Hospital suffering spinal injuries while the 10-year-old boy sustained serious leg injuries, the nine-year-old boy sustained minor injuries.

Police allege the man also attempted to run from officers after he was found at a home following the crash, but after a short foot pursuit he was arrested.

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