 In the early mono mix of the film, a few lines are slightly  different, or completely different vocal takes. For instance, a  different actress dubbed Aunt Berus lines in the earlier mono mix.  Likewise, Lukes line "Blast it Biggs, where are you" in the Death  Star battle was "Blast it Wedge, where are you" in the mono version.  Although the mono mix is less common, the version of the latter line  in it makes more sense, since Wedge was the one helping Luke in that  point of the battle.