It looks to me as if there was nearly a brockage, as the raised detail of the teeth is the incuse detail on the die. If a coin is not properly expelled between strikes, it will act as the die and leave an incuse detailed impression, because a die has the inverted relief, ie incuse is raised an vice versa, so to have raised 'incuse detail', it had to be a wrong-un, because the die would not have changed its relief and would strike normally, albeit off-centre. With several examples known, the detail must have been from a trapped coin.