To move the configuration from one ConBee to another I’d recommend to update the firmware first to the latest stable version 0x26720700. This is required so that the NWK security counter is transferred correctly, otherwise devices in the network likely reject commands from the new ConBee since they think a replay attack takes place.
With the latest firmware let the first ConBee run for a while, like 30 minutes.
Then in the Phoscon App create the backup, this should now contain the full configuration including the NWK security counter.
Now unplug the old ConBee and attach the new one and load the backup file.
Important don’t let both ConBees powered on at the same time since they would fight over the same network (two identical coordinators).
Hope this helps.