Identifier name (comma use)

https://opinionator.blogs.nytimes.com/2012/05/21/the-most-comma-mistakes/

I went to see Woody Allen’s latest movie, “Midnight in Paris,” with my oldest friend, Jessie.

The syntactical situation I’m talking about is identifier-name. The basic idea is that if the name (in the above example, “Jessie”) is the only thing in the world described by the identifier (“my oldest friend”), use a comma before the name (and after it as well, unless you’ve come to the end of the sentence). If not, don’t use any commas.

What about here:

Example: On June 19, 2018 it was announced that Del Toro and his partner, Cuarón would instead be attached as Executive Producers.

Based on the the article:

What is the difference in meaning between using one comma, as in this above example, and the notion of using two before and after. I've seen names with one comma like this quite often; instead of two. Shouldn't Cuaron have two ?