In some cases, Raspberry Pi's can malfunction and none of the USB ports are working, so it is not possible to pair wireless controllers. By changing the Bluetooth MAC address, you can synchronize controllers with other Raspberry Pi by duplicating the MAC address.
Connect via SSH and run these command lines:
wget https://www.tbit.com.br/files/static/bdaddr.gz
gunzip bdaddr.gz
mv bdaddr /bin
chmod +x /bin/bdaddr
Now you can change the Bluetooth MAC address with these commands:
bdaddr -i hci0 -r B8:27:EB:00:00:00
hciconfig hci0 reset
Edit or create the boot file at /recalbox/share/userscripts/custom.sh :
#!/bin/sh
sleep 2
/bin/bdaddr -i hci0 -r B8:27:EB:00:00:00
hciconfig hci0 reset