viloentluke is correct. The product page for the exclusive has two heads, the "collector's" or regular edition product page has one head. There is no third head.
https://www.sideshowtoy.com/collectibles/marvel-thanos-on-throne-sideshow-collectibles-3004341/...
Have you used a pop up code discount on something else in the last year? If so, that could be the reason since Sideshow changed it so that each account can only use one pop up code per year to prevent abuse of the codes.