However, my understanding of the different dialogue to which you refer is simply down to the different formats that the film was originally released in.
Go here to read more. (link borrowed from another thread)
I cannot say if the missing dialogue you refer to is a later addition or has it been removed at a later date.
From the link above............
Ben Burtt recalls: "Because we were always trying to make the film better and better and fix things that were not right, there was some 'sweetening' done; things like different Stormtrooper or C-3PO lines, additional sound effects, or some different ADR."
Now I have said my bit, I will wait for the experts to have their say and they really know their stuff!!
Good luck in BOTH of your quests!!