I should expect that they ought to mark each one with the voltage label to know what it is, if they do something like that.
(Using a different shape might be even better, to avoid plugging it wrong by accident or if it is dark and the label cannot be read or it is faded and cannot be read, etc, and you can more easily tell which device works with which plug because the shape matches the devices being plugged too.)
Multiple AC standards is just fine, so long as all the sockets are physically different so you can't screw up. Electricians are expected to know all the weird rules and get things right, but normal people can't make a mistake so it works.
Almost all US houses have two voltages, but since the sockets are obviously incompatible it all works. I've seen industrial buildings that have more than one grid connection (and in one case they paid extra to ensure the grid connections went to different sub stations)
(Using a different shape might be even better, to avoid plugging it wrong by accident or if it is dark and the label cannot be read or it is faded and cannot be read, etc, and you can more easily tell which device works with which plug because the shape matches the devices being plugged too.)