Those coils on the sides of the modules on the left are for autofocus, hence only 2 per lens assy. The coils for OIS are mounted on the bottom of the telephoto module (as you can see on the green PCB). The lenses wobble a bit because they need to be free to go back and forth to focus. There are designs that put the OIS coils on the sides, but it’s not the case in here, you need 2 for the y axis and 2 for the x axis. Those modules on the left only have VCM’s for the z axis.
Now every single news company is putting out articles saying that the P20 Pro has OIS in all cameras.