The 1977 bootleg features the mono soundtrack as Beru’s dialogue is different for the Lars dinner scene:
https://drive.google.com/file/d/0B8_LYKyZDiajNDAyT0tGTjVCd0E/view?usp=sharing
I wonder why they dubbed her voice…I find no reason for it, but evidently George did.
The on set dialogue recording was probably not good. Happens even in films today, though it tends to be a little more seamless now.
Sort of off topic, but there are parts of ROJ where the ADR really bothers me. Most are with Leia’s lines.