I was thinking about watching die hard 2 when I was perusing Amazon the other day. When I saw the subtitle die harder I was positive that was added much later after the fact. I remember joking about "die harder" back when the movie came out but it was a made up joke not based what was then a non-existent subtitle. I went back and looked into this and apparently I wasn't misremembering. The movie's name is just die hard 2 and only later was the marketing slogan added as some sort secondary title.