Pat, I also just noticed that all your White examples all have a printer's mark on front bottom border. Don't know if that helps anything.
As far as "who got into Howe's show box" it could also be that the "other marked" cards belonged to someone else, who then gave them back to Howe.
There were only two "Rooster Stamps" -- Brain and Myers, bat.
Others included --
A penciled "M" (maybe ~50)
A "what the heck" ink scribble, all of which, I believe, were on Baltimore cards (less than 10).
129.jpg
063a.jpg
Fun, fun, Scott
