Differences between two basedrums and a double footpedal

Fear Factory uses 2 basedrums.

Dream Theater even has 4 but I think that's because they are very progressive and may be using different tunings on them.

Between the Buried and Me only has one

The only reason I could imagine is the price because 2 basedrums + 2 footpedals seems to be more expensive than 1 basedrum and 1 footpedal. Both do very heavy music.

But honestly I don't know I never played drums myself.