This was in almost all their sets around 2008 or so. It was just a filler card to weigh the pack down a bit more so guys who pack searched thought they found a hit. It might be on the site somewhere, but I'm not sure it needs to be added to every set they were inserted in, as they aren't really unique, just a piece of thicker cardboard. I used to use them to seperate cards in my 3200 count boxes and binders since one side was blank. I could write on it and see what the cards were.
Royal Card Review is my blog if you feel like checking it out, thanks if you do!- royalcardreview.blogspot.com/
In the process of updating my collection so don't trust any of my lists right now.