Help Me Identify Washington 5c Blue.

Need help to identify this stamp. Reads a perf 11 and measures 19mm by 22mm. No gum. A scott# will be appreciated.Please ignore whatever written at the back as it does not make sense. All inputs appreciated. Thanks.

Scotts-504

Perf 11, Blue 5 cent, no watermark = 504

looks like the back says..value $7.14 cat# 505

Scott# 505 is an error stamp. 5c washington on a 2c plate.Valued unused 350 and used 550 as scoot 2008.It cant be this unless referred to some other cat.

This I believe: if somebody is dumb enough to write on the back of a stamp, they are dumb enough to mis-identify it.

This was an accepted practice back in the day, just like hinging mint stamps prior to the availability of mounts. It was, what it was, so it is what it was.

WW collection I am going through right now has SC#'s lightly penciled (very small) on every stamp of which there is about 50,000+++. Not something I would do but wow does it help sorting. Can not phathom the amount of time it took to catalog all these but it was the norm. Problem is once you find 1 mistake you become skeptical of all others. If you accepted this was a 505 because of the pencil marks you would be sadly mistaken unless it refers to different catalog.