I was reading my textbook and ran into this case: two ideal gases in a container are initially separated by a wall, with the same volume, the same amount (in moles), the same temperature, and the same pressure. When the wall is removed, the two gases will mix and each gas will have an entropy increase of $$ \Delta S= n R \log \left( \frac{V_f}{V_i} \right). $$
OK. But what if we have two exact same gases? Removing the wall seems to do nothing at all to me. I'm quite confused.
