Most of the file managers included in distributions have an interface which usually provides a left panel and a main widget to display files and folders, and some even have an option to split the view left/right, like Nautilus in GNOME or Dolphin in KDE. But they don’t follow this view mode by default, and usually they can’t save this choice so it will be displayed like this the next time the application starts (there are exceptions – see Konqueror who will use profiles and will be able to save interface changes). On the other hand, there are the twin-panel based file managers like Krusader, Tux Commander or EmelFM2, from which GNOME Commander is also a part of, with the twin-panel mode enabled by default.