US Scott Td 9 And Td10

Does anyone have any copies of both of these gummed and perforated U.S. blank stamps, especially multiples? The Scott catalogue says perforation 12 for both of them but I am looking to see if the sides of each different stamp multiple can be lined up perforation to perforation with each other to compare them or if the perforations on each different multiple can be more accurately gauged to at least one decimal point.

I have found the following picture of both TD9 and TD10 together.

At first comparison, it appears that the TD10 (12) perfs are of a very slightly lower gauge than the TD9 (12) perfs.



These may have been used to test the perforators.

Such as 1878 when the ABNC started printing U.S. stamps and George C. Howard perforators started to be used by them (TD9?).

Such as 1907 when the BEP started switching over perforators from George C. Howard to the Universal Telegraphic Company (TD10?).

There is a Canadian Admiral blank stamp which appears to be from 1912 which may appear to mark a point when the ABNC started to change over from George C. Howard perforators to their own ones.