I'll have to make some more careful observations, but there seem to be a lot of strange things going on with this combination.

First, when two Alps are both in the same spot and one moves they both do. I believe this is working as intented. However, in some cases they will leave mountains behind...I think this may depend on whether the first or second Alp is activated in the move.

Also, when double Alps interact with Flash Flood they will sometimes leave permanent water behind where it wasn't before the flood.