This is the result of what happens when characters are voiced by only a handful of voice actors. Often you might hear characters that sound the same.
Related to Only Six Faces
is probably one of the most famous shows to be voiced by a handful of voice actors for a majority of the main characters, though they are so good that this trope is subverted and all of the characters sound pretty distinct. Most of the adult male characters voiced by Dan Castellaneta, Harry Shearer and Hank Azaria. It's amazing that they all sound different.
Played straight with South Park
as Matt Stone and Trey Parker voice most of the characters. It's funny when a one shot character sound just like Mr. Garrison made funnier in other Parker/Stone productions when the same voice pops up again. Also played straight is Only Six Faces
also plays with this trope as the brothers Chap voice most of the characters though somewhat Justified
as there is only a handful of main characters.