When I finished my first sock I weighed it and picked a ball of the same weight to make the second. It was exactly the same weight which was not ideal as it didn't leave any extra to cover gauge variations or differences in the yarn. And I ran out with about four rounds of the toe to do.
This is not really a problem, I still have over two and a half kilos of this yarn left so I joined another ball in and finished the sock.
Two socks, and I even modelled them as requested.
Now I can pick my next project for this yarn, I am thinking about the cardigan next so I am going to have some skeining and dyeing to share.