Here’s Lend a Paw. The mini devil and angel don’t actually appear on Pluto’s shoulders, they just walk/fly around. Interestingly the same mini devil appears in Mickey’s Elephant (1936) without his angel companion.
I’m thinking that the origin isn’t really from the Islamic tradition mentioned above. It looks like Disney cartoonists simply first used the device of a tempting devil from the Christian tradition and from there it was natural to add an angel in the later cartoon. Presumably some later cartoonists put them on someones shoulder (though I’m guessing that innovation happened with a different character then Pluto since 1) The database I found of Disney characters doesn’t have any further appearences of the “Pluto’s devil” character till the '90s and 2) Pluto doesn’t really have shoulders). In anycase, I’d be interesting if someone knows when the mini angel/demon moved up to peoples shoulders.
Of course, that website I linked to might be wrong, and the Disney cartoonists might be drawing on an earlier instance of the device.
ETA: other interesting fact, while googling I found a Time magazine article about Lend a Paw that states the voice of the angel is supposed an imitation of Eleanor Roosevelt.j