Based on the description for this set it would seem to suggest that the cards are dated to the first year of the run (1907) due to the existence of writing on the front:
"While the Dietsche issue was sold over the period 1907 through 1909, we believe that all of these date to their initial (1907) appearance; last names appear on the fronts of all." In fact, the writing is just that -- someone writing on the card after the cards were created, having nothing to do with the dating.
http://www.legendaryauctions.com/Lot...d-and-Jennings