Info About Franklin 1 Cent Stamp?

I sell quite a few postcards and see a ton of Franklin 1 Cent stamps, but this one caught my attention because it was blue. Is it anything special? The postmark is 1907. I googled and saw other styles of blue Franklin stamps, but not this particular one. It's obviously in fairly bad shape so I'm assuming it's not worth anything...it's more just that I'm curious about it since I don't remember ever seeing one.

yellow + blue = green
The red/yellow end of the spectrum will light-fade more quickly leaving blue behind.
Thus in addition to the physical damage, there is light damage. It is not an error.

It is called a 'color changeling' (as John mentions, a light damaged stamp). More info here
https://stampsmarter.org/learning/A...gelings.html
Don