def get_system_name_mappings(column_data):
    """
    Given a column_data dict, get dicts mapping the system_name
    to the display name, and vice versa.
    """
    system_name_to_display_name = {}
    display_name_to_system_name = {}

    for key, entry in column_data.items():
        if entry.get("system_name", None) is not None:
            system_name = entry.get("system_name")
        else:
            system_name = key

        system_name_to_display_name[system_name] = key
        display_name_to_system_name[key] = system_name

    return system_name_to_display_name, display_name_to_system_name