Think it is necessary, or a code requirement, to ground the lower box also ?

It is just providing some protection for the wire nut splices of the house
wires coming thru the wall, and the new wire run up inside the conduit.


If you were running the cable straight through the box,
I'd have said "no, it's not worth grounding it.". But
if you have a splice in the box, then there's no reason
*NOT* to ground it. You've already cut into the cable.

-Goedjn