Sc# 1927 Maple Leaf Coil Stamp

Hello all,
I have just recently finished sorting/inspecting about 5000 used copies (whew!)of this issue and found that I could easily find 3 distinct levels of fluorescence on the back of the stamps (NF, DF, LF). When I turned them over to inspect the printed side, I again could separate them into these 3 levels (although not as easily). The breakdown I got was NF 15%, DF 54% and LF 31%. The Unitrade catalog doesn't mention any different fluorescent levels for this issue (front or back). Has anyone else been able to find these different fluorescent levels? Also, I have found 5 examples of all-over speckled tagging ink, as shown in the photo.

Cheers.

Can you include a scan of the stamp without the UV?

Have you tried this with mint stamps?

I haven't been able to dig deeper into this with mint stamps. I only have a strip of 4 mint stamps (NF) and nothing else (hence the request from others to confirm this).
Here is a picture of the stamp (without UV)

Cheers!