My Makita Systainers have "Licensed by TTS/Tanos" stamped in the plastic. These are the real deal for sure.
As far as any other style if they are not stamped licensed by Tanos I doubt they are. I only have the larger units and they are all stamped. By the way the rounded corners ARE Tanos boxes for sure, all my stamped Makita boxes have the rounded edges and are stamped TTS/Tanos.
Buy them, in my experience they are just as good as any other non T loc Tanos cases. The Systainers are not that durable anyhow. I own so many, but they are not near the quality of many other cases I have. I would never use them as a step stool, that's for sure.