Directly replicating it from one device to another device is cool, but I like to back up my setup to a file, this worked for my, not sure about other,
I would subscribe to the topic (default is metrics/exchange), I use mosquitto
/usr/bin/mosquitto_sub -h mqtt.example.local -t metrics/exchange -u john -P JOHNsweakPassword
Then I would got to the app and click the UP and DOWN arrow and publish the metrics.
a really long payload starting with [{" and ending with }] would appear. Copy that, that is your backup.
When you are ready to restore put the device into "subscribe mode" and publish, use single quotes around your settings
/usr/bin/mosquitto_pub -h mqtt.example.local -t metrics/exchange -u john -P JOHNsweakPassword -m '[{"SOMEREALLYLONGSTRINGWITHDOUBLQUOTESANDTOTHERTEXT }]'