The copy rotates and then turns invisible. The original becomes visible at that point. So it generates an illusion of movement by showing the rotation (which alternates every few seconds with the non-rotating version).
If you want to see it better explained, go to inspection mode and change the size of one half of the pair.
(Try CENTER and CENTER2) Set CENTER2 to WIDTH: 101 and HEIGHT: 90 (this makes it roughly half the size of the original
You’ll see the larger hex not rotate and then disappear, at which point, the smaller one will appear and start to rotate. When it finishes rotating, it disappears and the original reappears.
And again, Tomas is the one who came up with the code, he deserves all the credit.