I did see that - I'm a bit surprised because I measured the 8.4 Kanfoush and its exactly 8.4. I'm starting to wonder if this shape is a unicorn.
The best example I have to offer, is when I did have about ten or so of the same board, some from the same run as well as other runs, lined them all up sitting on one side so I could see the concave and pull out the more mellow ones to ride first, I did also notice slight differences in the widths, some a bit wider, some not so wide and could feel it when I ran my hand over the stack, but could not feel any difference when actually skating them, even when the difference between two boards was about 3mm.
It might mess with your mind, but when you have it under your feet, it will still feel exactly as it should.
The other thing too is in the measurement details, eg how a board is measured or if the tape measure has a longer lead in the hook end or getting it right on the edge / middle ply vs sitting on the top ply (can be a difference of +4mm too I saw between two different tape measures when we had a bit of a measurement crisis in the shop one day) but I guess it also comes down to whether or not you can buy in a shop or have to order online too.