def METHOD_NAME(self):
    """
    Checks for duplicates in all objects.
    """
    duplicates = []
    for instance_list in [
        self.track_sections,
        self.switches,
        self.links,
        self.operational_points,
        self.routes,
        self.speed_sections,
        sum([ts.signals for ts in self.track_sections], []),
        sum([ts.waypoints for ts in self.track_sections], []),
    ]:
        seen_ids = set()
        for instance in instance_list:
            if instance.label in seen_ids:
                duplicates.append(instance)
            else:
                seen_ids.add(instance.label)
    return duplicates