Regarding the duplication issue, instead of removing this bug, we could try to create a fix for it. Asm mentioned that this is because the hero is stored in the save file (and in memory) in two places – in the list of heroes and in the list of map objects. The duplication occurs because the coordinates in one place differ from the coordinates in the other, causing one of the copies to "stick." Accordingly, it can be fixed by removing the copy that remains on the map. It's a bit more complicated with castles if the hero duplicates while inside (this often happens with companions). In other words, instead of eliminating the cause of the bug, we can create a fix that activates when the bug occurs.