A 1929 Babe Ruth “Star Picture Stamps” Exhibit was recently sold on ebay here: 
Link.  I was not the winner of this card, and I've attached front and back scans.  This card has a coupon back on it, which I have never seen before.  Has anyone else seen one of these before?
Typically, this card has a postcard back.  Here's an example: 
Postcard Example
The coupon back normally does not appear until the 1931-32 Ruth Portrait Exhibit.  Here is an example of a coupon back: 
Coupon Example.  And here is an example of this card with a postcard back: 
Postcard Example.  The regular 1931-32 Exhibits also have coupon backs: 
Link.
Does anyone know how why this card was dated to 1929?  Perhaps, it should be dated to 1929-31 or even 1931-32 like the other Coupon back Exhibits.