I solved used Sixasis Pairing tool from Windows, i forced my "problematic" Shanwan to connect to Raspberry BT address.
Now i have the problem that all 2 shanwan copies are detected as "Playstation 3 original" , but i selected Shanwan drivers from configuration and i read that supports "original and shanwan" , so at the moment i cannot see any issue with this.
Recalbox is free and support is not expected to be given quickly, i just ask if somebody can shed light about where BT pairing informations are stored, why Shanwan copies are detected as Ps3 original and so on.
In the FAQ, in the tutorial we can add Sixasis Pairing tool way for problematic controller, i can give my availability to improve the community experience.
I also had other issues with Ps3 ORIGINAL pad (that now i use only with Android phone), this device often pressed buttons, never really pressed! Led often stay OFF, but pad was working (with ghost pressing issue).
I thought was a problem with pad, but with Android works like a charm, maybe if reoccurs with Shanwan units i should open another thread.