I've a save from 0.14 and when I take the map exchange string and generate a new map with it, I get a different map (but always the same).
Some details:
On 0.14 the map exchange sting is:
map exchange string 0.14
This gives this seed on 0.15: 2693220248 and this map:
map
On 0.15(.22) the save gives the following map exchange string:
map exchange string 0.15.22
This gives the exact same seed and map as the map exchange string from 0.14, but this map is really different from the map in the orriginal save.I've attached the original save game.