Running into this a lot in my current game. If I have a mustache golem out and kill a monster with other monsters around, sometimes the golem and another monster will move into the same tile. Usually when this happens the tool tip and art will not match up, meaning that if the art shows the golem, the tooltip will describe the monster or vice versa. Either way it seems as if I'll attack the golem every time if I try to click on that tile. Havent seen anyone else mention this so I dont know if it's all pets, just mr mustache, or just a weird occurrence in this game.