Catalyst Control Center: really needed to be installed ?
I didn't yet try to install 12.8, excluding CCC.
The situation is that the CCC system try icon, even after uninstaling
completely the AMD drivers (all), also using driver sweeper 3.2.0, in
safe mode, when restart and do a clean install, the CCC system tray
icon, if right click shows... 12 AMD Radeon HD devices, when in fact
there are only two (6990) !
Also used ccleaner, just in case and manually search and delete what
I could found about ATI or AMD folder (even if hidden).

After rebooting the installation work with no errors.

How to clean this mess ?
Crossfired isn't used. Might this causing some issues on CCC
behavior, somehow ? Or, perhaps, CCC isn't really needed; can
try to exclude while doing a new clean install. But having some
opinions may save some precious time.

Last option, but really last one, a complete clean OS installation
would put things running the way it's expected.

Device manager shows 4 GPU. This is what is there.
Perhaps this is hapening because the hardware had been
unppluged to change coolers, and weren't place back in the
same slot again. Can this cause CCC weird info ?

Any advices are welcome.
Thank you.

Edited: About the adl_overdriver5_temperature_get(): -5 that
I report not long a go, I did a try using the option --gpu-temp-disable,
and there are no error message anymore, and now the last beta with
this option works well.
Beta did not change anything to this. I am sure you fixed it due to experiments with the drivers, which is known as the cause for adl_overdriver5_temperature_get error.