SDI2 devices that are of the same typemust use differentaddresses.
SDI2 devices that are different types can the same address.
For example, a B820 and B426 can both be set to address 1 because they are different device 'types'. However if B426 and B450 are connected to the same panel they must be addressed differently because they are both the same 'type' of device. Also a B208 and B308 could be set to the same address because they are diferent types of devices.