It worked both ways and was nothing more than a poor attempt to give Mitrovic a trial by replays - especially by Don Goodman.
The incident when he was booked was comical and then ,albeit a touch over zealous, he had every right to go for the ball on that second one. But for the latter he should have been booked as he left his foot in. Essentially the ref just booked him for the wrong challenge and if it had have been a Wolves player, he'd have been praised for using his 'experience'.