It seems that these small differences in the results are not due to flavor additives but are the result of the use of tobacco mixtures or tobacco with noticeable differences in tobacco radioactivity
And those two things are not unrelated

The TSUPCP oversees the states prevention services, including the newly establish statewide Maine Prevention Network, a collaboration between multiple programs of the Maine CDC and district-level community partners to implement evidence-based prevention programming with the purpose to: Prevent and reduce substance use, misuse, and related problems Prevent youth and young adults from starting tobacco use, encourage tobacco users to quit, eliminate non-smokers exposure to second-hand smoke, and identify and eliminate disparities related to tobacco use among population groups Increase the number of people in Maine who are actively working to implement national recommendations included in the dietary and physical activity guidelines for Americans Increase resiliency and reduce risk of commercial tobacco use, substance use, and unmet mental health needs among youth Measurably improve health outcomes associated with substance use, suicide, tobacco use, and tobacco exposure Ruth Dufresne, M.S., senior research associate, will serve as principal investigator and lead evaluator on the project

Do menthol cigarettes increase cancer risk