 While the original 2003 release had a different voice for Bob, the film  originally also had different voices for Donna Lewis and Cindy Bayer as well.  All three of these voices were replaced for various reasons, but the most  obvious reason for Bob and Donna was the decision to use actual actors (in  this case Sara Escobedo and Nicholls Melancon V) rather than friends or  friends of crew members so as to get a better performance.