It looks more like NR is being used to either bridge or simulate the data of two different devices and they need to each have their own connection to the broker using different authentication credentials.
Sounds perfectly reasonable to me
@e-infotech as Steve mentioned, you need to give each Mqtt node it's own broker config node. At the moment, they are sharing the same config node, so any change applies to the both
Pick one of the nodes and open its edit dialog. In the drop-down select box for the broker, select "add new mqtt-broker", then click the button next to it. That will create a second broker config node for that node to use. Make sure you give each broker config node a name so you can identify them in the select box.
