Originally posted by Cipher
I've thought about that myself and have two ideas: first, there other protocol droids with the same voice. Second, maybe Owen suspected it and that's why he was adamant about erasing the droids memory.
Remember that droids in the Starwars universe are just appliances. I personally wouldn't recognize the toaster oven I owned 20 years ago... Although it would make sense for Owen to have that attitude if by chance he did remember 3PO.
Also, my two bits...R2s memory remains intact. "I've never seen such devotion in a droid before." My guess is R2 knows exactly who General Kenobi is.