Richard Pearson, aged 43, pleaded not guilty at Stafford Crown Court to gross negligence manslaughter.
He is accused of causing the death of worker Simon Hillier and customer Stewart Staples.
Both men died following the fire at SP Plastics in Baswich on October 30 in 2014.
Pearson, of Holyrood Close in Stafford, will return to the court for a trial in April next year.
Mr Pearson, was himself critically injured in the blaze which killed Mr Hillier, 41, and Mr Staples, 57, both from Hednesford.
Mr Hillier, a father of one, and Mr Staples, who had three children, died after flames engulfed the industrial unit in Tilcon Avenue. Fifty firefighters battled to contain the blaze.
In tributes issued after their deaths, Mr Hillier was described as a fantastic son and brother and a ‘terrific’ father, while relatives said Mr Staples, a laboratory manager for Staffordshire County Council, was a devoted family man.