[davidmanze]

Well all depends on each specific camera design and where the malfunctioning is.
Twin card was made to avoid losing pictures after a card fails  not a rescue feature if one of the card slots fails.
So nothing says in all cameras each slot has a
totally dedicated  circuit and wiring and you might actually have a simultaneous failure of both card slots since they have some shared components

  I think in this case there are two circuits, one for each card ..... although the problem here is not electronic.

  Looking down the Sd slot I find t a plastic lug which is what pushes the card out, this can be pressed but just like with the card the piece just won't stay in ... it seems that this piece also doubles as the switch to connect the card ..... holding the card in does not connect the card to the camera.
  It is spring here and I just don't want to miss any birding and shot opportunities or make things worse ......  there's winter for that sort of malarkey! .....

P.S. Now I have the same number of cards slots as JoJu's Z7 ...... so I guess I've made it in life ....