Etched brass plate Rex Harrison movie scene 1946-Signed Keye Luke

I came into possession of this brass etched plate measuring 10 3/8 " X 7 6/8 " depicting Rex Harrison in a pose from the 1946 movie
Anna and the King of Siam. The item has a etched name Keye Luke;
Who was a movie poster artist and a actor for seven decades in Hollywood.
He played Charlie Chans #1 son, Kato in Green hornet and many many other movies and TV 1934-1991
I am at a loss as to why this piece was made and did it have a special
function. Any help would be greatly appreciated.