A coal mine explosion that killed 29 people...could have been prevented, US Department of Labour officials said on Wednesday...MSHA [Mines Safety and Health Administration] also said it discovered that the mine kept two sets of records, with reports of hazardous conditions often left out of the official books...Alpha Natural [which has acquired the mine's operator, Massey Energy] will look at the information made available by MSHA as part of its own review of the incident at Upper Big Branch, Alpha Natural spokesperson Rick Nida said. "We heard this information from MSHA at the same time that everybody else did," he [said]..."Our review is really in the early stages, we are just starting to assemble specialists as part of the team. And when the full MSHA report is made available, it will be part of the information the team reviews closely."...Eighteen managers from Massey Energy and subsidiary Performance Coal declined to be interviewed [for the govt. investigation]...