I too examined the strip at the National. I could see nothing that indicated to me it was created by pasting together multiple images. I believe it to be one continuous strip of cards printed at the same time.
Looking closely at the image you can see several printers marks on the strip. On the left and right of each image there is a "+" mark. On the top of each image there is a "+" mark and on the bottom there is a "l" mark. But most importantly concerning the main focus of this thread, there are "l" marks between each image top and bottom with most falling directly on the line separating the images. The one on the bottom between Bowerman and Young falls just off the line. Several are not visible as creasing has destroyed them. These marks IMO show guidelines used in the printing process for maintaining the proper separation between each image that was being printed at the same time on the same strip.
