My understanding is that with the stock calibration from Harley the fans are staggered, as in the first fan kicks on at one temperature, then the second fan joins in when the temperature rises to a second level. There's a thread around here somewhere in which Steve Cole, the TTS MasterTune expert, explained how they are set up from Harley, and how he sets them up differently in the TTS calibrations (maps).
Btw, having the fans staggered like that isn't unusual. Many cars have been set up that way from the factory, with two radiator fans and the secondary only runs under certain conditions.
Jerry
Update: It seems I have that backward, according to Steve Cole. Harley has them set up to run together, but the TTS is set up to have them run staggered, with the left coming on first and the right only coming on if the temperature continues to go up. Sorry about the bad info.