Another T206 back "mark" thread (EPDG)

[steve B]

That's a really interesting mark, At first I thought it was a poorly erased bit of Sweet Caporal back, but it doesn't match up all that well.

Originally Posted by Pat R

This is just an opinion based on the statistics I have on several
print flaws but I think most of the non Piedmont and Sweet Caporal
sheets had fewer vertical rows of the same subjects for example
a Frank Owen flaw is found on 3 out of 5 EPDG's but the same
flaw is found on only 13 out of 152 Piedmont's and other flaws
have comparative statistics when they're found on one of the
uncommon backs.

The really common backs I believe were done in multiple identifiable press runs. That would skew the numbers to make it look like a larger sheet.
But different sheet layouts certainly are possible and in some cases likely.