Just for info; one car needs 4 parts. Each front seat has a left and a right part.
I've personally never seen the alu version ones; can anyone confirm if they are e9? Perhaps early only? One thing that makes me wonder if they are perhaps not e9 is that the thin alu ones have a different bolt pattern. If they would be e9, it would mean that the bottom of the seats would be different over the years.
So if I see it correctly, the 4 parts in your pic would be / could be good for one car.
However as they are different materials and, as I deduct from the pictures, also have a different thicknes. It will result in different heights of the seats if these are installed in a single e9.