Kaa is the only character to have the same voice actor both as a hatchling and as an adult.
According to Jason Marsden, Shere Khan as a cub was at first intended to have a British Accent like his adult self, but Disney later decided otherwise, leading to an American Accent like the other characters. This was also the case with Hathi.
In the present time cutscenes of the DVD "Born to the Wild", the Main Cast of Characters as Adults (apart from Shere Khan, who was voiced by Tony Jay, who continued the role up until his death in 2006) were all voiced by Jim Cummings.