Owen knows about protocol droids but he is obviously dis interested in them so why would he remember a droid from 20 years ago. Owen doesnt strike me as being the observant type.
And as for the droids memories, owen does mention having their memories erased in ANH, maybe it is a common thing when droids change masters. Especially when you consider that they started to work for the rebellion, i would have had their memories erased - there are a lot of espionage droids. Maybe it is an insurance policy against being spied on.
I am still not sure that R2D2 has his memory erased though. C3PO must though, the name Skywalker would be remembered by him you would think.
i can be white today and tan in 20 years but im still the same person. same characterisitics same personality. color does not matter.
i think amidala is right, c3po probably got his memory erased every time he changed masters.
r2d2 though is the key witness in all starwars movies.
if the starwars movies are being told today by some third party involved in the starwars universe iŽd think it is r2d2 who tells the starwars story.