The case of the empire strikes back film is interesting. I've watched the French dubbed version on TV a few times and at school we used to joke (imitating Darth Vader's voice): "Luke... je suis ton père" ("Luke... I am your father"). I haven't seen that version since then and I'm not sure the copy still exists since everything has been replaced with newer digitalized versions. When I watched the film in English years later (digital form), the line "No, I am your father" didn't sound right. Maybe it was re-dubbed during digitization, maybe something glitched in reality, or maybe unrelated kids everywhere instinctively came up with a more dramatic line.