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I don't know what to call it, a feature or a bug. Most likely, it's a bug. So, my brother and I were playing on the same computer in a cooperative mode (Hot Seat) against the AI. My hero was in the castle, in the garrison. My brother's hero entered my castle and stayed there – either he didn't have enough moves left or he needed to replenish his mana. It was my turn. My brother's hero blocked the exit, and I needed to move. I entered the castle and simply pressed the spacebar. Our heroes switched places. My hero ran off to do his thing, and it was my brother's turn. He exited the castle with his hero, did his thing, and skipped his turn. And here's the catch: my turn started, and – lo and behold! His hero ended up in my ranks. I played a turn with him too. We thought he had simply switched owners, but that wasn't the case. My brother played, and it turned out that the hero was also with him. The hero was, in effect, owned by two players at the same time. We caused quite a bit of chaos with him.