Here are a couple examples of Scott 65a in distinctly different sizes.
The Scott United States specialized catalog lists 65a in a number of colors, dull red, rose red, brown red, pale brown red, and dark brown red, but it makes no mention of any stamp size on any example of the many stamps illustrated as A25 in their catalog.
Here are two copies of 65a shown side by side; the difference is noticeable.
The stamp on the left measures approximately 22-1/2 X 25-1/2 millimeters. The stamp on the right measures approximately 21 X 28 millimeters.
Does anyone have any insight or information on this?