Hollywood legend Robert Duva ... ?

Some people claim to remember the spelling of Robert Duvall as "Robert Duval".

There are many references on the internet to "Duval" which make it clear the reference is to the actor, and not someone with the actual name "Robert Duval". 

His movie roles go back to the early 1960's when he appeared in To Kill a Mockingbird, then MASH and George Lucas's first role as a director as the lead in THX 1138. Since those, his appearance in The Godfather movies, and the Vietnam war classic Apocalypse Now, alongside his equally prolific TV work has confirmed him as an A-lister.

The unusual spelling of the surname likely lends itself to interpretation when spoken, because both variants sound the same. Yet those who swear it's changed claim they were well aware of how it really was spelt originally.

Robert Seldon Duvall

Described as "the most convincing actor on the screen", he often played ordinary people in a way which had you engaged from the first impression. He was born in California in 1931, and his first roles were in TV in the late 1950's. His later roles in MASH and Apocalypse Now were no doubt made more authentic as a result of him being able to draw on his Korean War experiences following a 2 year tour in the 1950's.

Reference

A video from Recall Vector illustrates many references to the "Duval" spelling. Many of these are respected publications, where mis-spelling a Hollywood legend's name would not normally pass the level of proof reading expected, were it a genuine mistake.

Pronunciation

There are many Mandela Effects of this kind, where people know how a name is spoken, but pay less attention to how it's written down. When both spelling variations sound the same, it's often pointed to as the logical explanation.