In colleges, professors teach how to do research. No copying is allowed. Even when it comes to using someone's work, we are to provide citation. Otherwise, F may follow. Aamir Khan never went to college. Probably, even the director of Dhoom 3 had the same fate. So they simply chose to copy. Yes! Dhoom 3 poster is copied from Dark Knight 2's poster. Here it is:
Here is another funny one. Do look closely.