There are various disguises in various movies, including series like Chan and Moto, the best example being the Zodiac menage: Cesar Romero is supposed to be both Rhadini and Dr. Zodiac. Trevor Burdette is supposed to be the Zodiac's Turkish servant but Dr. Z when Romero is Rhadini.
Gerald Mohr is actually the "good" doctor when Zodiac is in scenes where he actually talks to Zodiac. (Those of us who are familiar with his voice and looks can tell. I luckily got confirmation from Kay Linaker herself that you can see at my link below.
This is something that has bothered me for a long time: Many of us are so familiar with the actors in these old movies that we CAN tell them apart by at least their voices when they try to pull off "double disguises" like in Paris and Murder Cruise.
Then there are movies like Mr. Moto Takes a Vacation where Joseph Schild***** plays Manderson, an old, bent-over cripple. Anybody as good looking as Schildraut so hidden in a character like that . . . something's got to be up.
So should Hollywood different actors to trade off on playing the double parts, hire twins, or use some other actor's actual voice to further hide the actual actors?
What to do in the other case? Beats the . . . stuffing out of me!
I feel that it would be a challenge to the actor or actress to use his or her own abilities to "pull it off" rather than relying on the use of someone else's voice. That would be my personal preference, while the alternative is acceptable, of course. We have seen "switched voices" on countless occasions when singing is involved, yes?