They already served the time but there was an issue with the sentencing from the first trial and they have to serve the remaining time. Source: http://www.vox.

They already served the time but there was an issue with the sentencing from the first trial and they have to serve the remaining time. Source: http://www.vox.com/2016/1/3/10703712/oregon-militia-standoff http://www.vox.com/2016/1/3/10703712/oregon-militia-standoff > The Hammonds were convicted of arson in 2012 for setting fire to public land adjacent to their ranch land. They have already served prison sentences for their crimes, but they now must return for an additional term after federal appellate judges said they had been illegally sentenced the first time.