Hi Stéphane,
We tested this on Windows 10, and it seems to be working for us. We first installed WindX plugin 2019, and the registry showed the 2019 folder, and then we WindX plugin 2020, and the registry updated to the 2020 folder. We tested for 32 as well 64 bit versions for the WindX plugin 2020, and both are updating in the registry.
Maybe you can try to refresh the registry again and see if that reflects the changes.