I am going to follow, and be interested in, other’s comments to this suggestion.
I think the idea is novel and not without merit. There are most likely a few use-cases for a display to present both units. However, I will be shocked if there is great demand for this feature.
An interface like that would be confusing.
I could imagine a user-interface that had the option to flip back-and-forth at a certain interval. With a quick-visual-clue to key the user what units are currently being displayed.
if you set the interval to 25 seconds: every 25 seconds the display would refresh and display Fahrenheit one time and Celsius the next time, etc…
I am personally multi-units in everything that I do, and support this request enough to spend a vote on it.
For a alternate idea, having the ability to add both metric and imperial units as separate cards in the station data screen would probably require minimal coding changes…