Canada 15 Perf Variety?

Hi all - I bought a few stamps recently and in checking them found this #15 that is perf 12 horizontally, but closer to 12.5 vertically. I can find no mention of this perforation in the first cents issue in Unitrade. Does anyone have a better reference, or care to comment, or check some of your own stamps? How much variation from 12 could there be? Is it possible it is re-perfed? (Both vertical edges measure the same.)

Using a Kiusalas Canada perforation gauge may help to determine what perforation measurement it may be.

There are variations on the perforation of this stamp as 4 different perforation machines were used over time. They are generally as follows :
1859 to mid 1863 : 11 3/4 X 11 3/4
1862 12 X 12
mid 1863 to mid 1865 11 3/4 X 12 or 12 X 11 3/4
1865 to end 12 X 12
These are just rouded numbers as perforation of 12.15 are normal