Weather Underground and two Tempest on one hub?

I have two Tempest one that at the moment is in sleep mode and has one faulty sensor and its replacement which is working fine. When the ole hub comes back to life with more sun then i will have two feeds on my hub. What happens to the data feed to Weather Underground, what data does it use?

They have different names and each one will appear under its own name.

I realise on the Weatherflow app that they appear as different names and data, but what about when that data goes to WU as it takes one data feed from Weatherflow.

It depends on which one is the primary device. Which one displays on the forecast page? That is the primary device. You have to request WF support to change which device is primary. The primary device(s) is(are) the first linked to the hub.

Great that answers my question.