Here below is an example of what I believe to be stamps of 1905, i.e., vertically laid paper with Burelage II. A shift downward during the printing of the main design has allowed the dotted background to encroach into the white space of the numeral circles. You can also see a white space above the crown, showing again a downward shift of the printed design.

Oddly, I have not yet found a clear example of the 1902 series (vertically laid with Burelage I). Nigel, I think, provides above a good description of the sort of shift to look for: the printed circle frame encroaching into the white space of the circle. My stamps show so far only the burelage dots crossing over that circle frame and into the white circle. Online I see apparently knowledgeable sellers offering as stamps of 1902 what to my I look like stamps of 1905. Yet my copy of Zagorsky indicates that the stamps of these two series should be equally common.
Here's a scan that shows more clearly the white space above the crown.
