Phoenix Darren John Tims and Atem Akoi Thon both pleaded guilty to two counts of arson causing death, car theft and arson of the car, and were both jailed on Monday for seven years and six months with a non-parole period of four years.
Co-offender Semaj Cigobia, 20, who pleaded guilty to assisting the pair evade police and car arson, was convicted and handed a two-year community corrections order.
Tims and Thon, both aged 20, admitted driving to a Sunshine North factory in a stolen ute in the early hours of February 23, 2024.
Tims poured petrol at the entrance of the property and set it on fire before the two men fled.
Hai Minh Nguyen, 41, and Phuc Tran, 48, were sleeping in a neighbouring property when the blaze spread and killed them.
The prosecutor accepted Tims and Thon did not intend to set fire to the property next door and did not know there were people inside.
In handing down her sentence, Victorian County Court Chief Judge Amanda Chambers said the offending was extremely serious and required a sentence that would send a clear message to others.
"This case tragically highlights the very real dangers inherent in arson attacks and the terrible consequences that can result when fires are intentionally lit," she said.
The two men had been promised $6000 by an unknown person if they firebombed the factory but they never received the money, the court was told.
The day after the blaze, Tims, Thon and Cigobia set the stolen ute on fire about 50km away in Coimadai, near Bacchus Marsh.
Police began covertly monitoring the offenders in July 2024 and recorded Tims admitting he "burned the place down" and discussing the fact two men had died.
Judge Chambers said the pair engaged in the arson attack at the behest of others who have not been identified and they had no personal knowledge of or grievance against the owners of the factory.
"Your motivation for your involvement, it seems, was merely the promise of some form of financial reward," she said.
Financial losses caused by the fire at both factories are estimated to be over $2 million.
Judge Chambers took into account the pair's "extremely difficult" childhoods that involved traumatic events, instability and violence.
She accepted Tims' good prospects of rehabilitation, provided he engage in support programs to prevent him from relapsing into drug and alcohol abuse.
She said Thon's lack of prior criminal history boded well for his future but was guarded by his risk of reoffending due to his ongoing cannabis and alcohol use.
The chief judge said Cigobia had reasonably good rehabilitation prospects if he can abstain from cannabis and alcohol, and separate himself from negative influences.
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