A few things:
Wagner, Plank, Carwford (Throwing), Lundgren (Chicago) and Jennings (Portrait) were not included at the beginning of the 150 Series. These subjects are all absent from initial print runs that included the Sovereign 150 backs. Only the original 150 Subjects were printed at this time.
Besides just the back data two collections that were assembled during the time the 150 Series was being distributed support this information. The first was the collage that was auctioned recently. It included all of the original 150 Subjects with the exception of Kling, but the five noted subjects were not present. Steve C. did a nice write up explaining it in post #7 of this thread:
http://www.net54baseball.com/showthread.php?t=145675
The second was a collection that was shared with me after the collage thread that included all 150 original subjects as well as Lundgren and Jennings. But no Plank, Wagner or Crawford. These were assembled similarly to the collage that was auctioned and hadn't been removed from where they had been since being collected. They really are a great snapshot of the set at a given moment in time.
Of the initial twelve proposed to be the first cards printed in the T206 set in the OP the above address Wagner and Plank. The ten remaining on this list were not printed or produced any differently than the other 140 of the original 150 Subjects during the 150 Series. One of the last 150 Series printings was brown Hindu and all 10 of these subjects were included in that back run. The only thing that sets these cards apart from the other 140 is that they were discontinued when print group 1 began being printed with 350 Series backs.