I don't know if this is relevant, but I've encountered a similar bug. Place a hero near a Castle. Restart the game. And you get two identical heroes, although you can't control the second one.
I can confirm that this glitch occurs with the following sequence:
1. When you enter a Castle with a hero and the game disconnects (70-80% of the time), the heroes duplicate:smile30:
2. The whole thing is that this kind of duplication happens due to desynchronization of this specific instance of the hero entering the Castle (most often in single-player or in a "hot seat" game)...
3. In the case of changing the graphical image. That is, switching from a large view of the map to a larger view of the Castle, and at the same time, the factor of the game's duration...