Thanks for the information. @billyb thanks for the link to the other thread.
I have shown a few people the picture and there seems to be 2 questions that I'd love any help with:
1. Is it possible that the autograph is a facsimile? It is certified by PSA/DNA (besides for the cert on the picture, there's a separate cert on the signature.) Looking under the light there is a definitely imprint where the pen went (including the look of the "h" in "Johnson" and a look at the end of the "W" in Walter" where there is no ink) so that seems to be an indication that it was done by hand. (I'm also not clear if there is a way to get a facsimile auto on a Type 1 Photo since it is being printed from the negative, but I'm definitely new at this.
2. Is there anyone who might be able to help ID the two people in the photo (who are not Johnson...)
Here is the front and back:
