Taken from Yahoo!'s Most controversial Star Wars changes of all time
http://uk.movies.yahoo.com/blog/article/252599/most-controversial-star-wars-changes-of-all-time.html
Boba sounds different ('Star Wars Episode V: The Empire Strikes Back', 2004 DVD Box Set)
Thinking that Boba Fett must sound exactly like his dad, Jango (from 'Attack Of The Clones'), is ridiculous. Nonetheless, Lucas went ahead and overdubbed all of Jason Wingreen's's original dialogue with new recordings by Jango Fett actor Temuera Morrison. No-one has ever understood why.
People didn't understand that he wasn't his son, but a clone who wasn't given growth acceleration. It's perfectly fucking understandable and logical why he would sound the same.