You are right Mateusz! There are Slovene, Croatian, Serbian, Bosnian and Macedonian. But apart from it, we have many similar examples in Europe, such as Danish, Icelandic, Swedish and Norwegian in Scandinavian case, then Czech and Slovak in ex Czechoslovakian case, then Belarussian and Ukrainian in ex Soviet case etc. Some of them are more, some of them are less mutually inteligible and understandable, but they all have their own ortography. I am speaking from the linguistic point of view, hopefully I won't be misunderstood again....
Plus I think these things should be cleared once for ever, finally.