Without getting into the particulars of 'how' these books were found, or 'why' they were posted on Facebook, there are some big issues with the books in the photos.
The paper stock looks incorrect, and the wear and soiling looks manufactured compared to 'real' Action Comics #1 comic books.
But the easiest way to debunk these books is to compare them directly with real books and look for tell-tale signs of being inauthentic.
So, let's start by looking at four of the highest graded copies of Action Comics #1.
Now let's take a close look at the font on the top edge of the front cover for each book and compare them to the two books in the Facebook photo (labeled LEFT and RIGHT).
You can easily see that the font on the two Facebook books is NOT the same as the real books.
The biggest 'tell' is the width of the font in the areas marked in red in the comparison chart.
Pay particular attention to the area inside the 'U' and 'J' of 'JUNE" and how much wider the fake books are compared to the real ones.
DEBUNKED.
I said good day!!!