Wt1, what you think?
The post from Saarland would not generally qualify, as a different country's name appears on the stamp, so it's not the "same stamp". If you do want it to qualify, then you would have to open up the thread to joint issues from different countries, which would always account for denominational differences.
Likewise, the second post on this page, showing stamps with a mechanical denomination imprint would not qualify, as anyone would have been able to make them for virtually any denomination.
The third and fifth sets of stamps shown on this page are of different colors (either the color of the stamp or the color of the denomination), so as referred to earlier, the color variations would not qualify.
The set of stamps from Canada would qualify, as the design and colors are the same but the denomination is different.
As alluded to earlier, the US (and many other countries) have series of stamps (primarily postage due stamps) that have multiple values within the same stamp color/design, so this post could expand significantly if all of those BOB items were to be included.
Just my opinion, of course.