Over the past couple of months, I've been going through some of my old purchases from estate sales and auctions of which I found many early 19th century postcards. This activity has now given me the fever to know more about stamp collecting even though the more I read the more complicated it gets. I have a question about these two stamps. The one on the left looks to be possibly a Washington 1918 #502 and I'm uncertain about the one to the right which is has a variance in color and detail. Any help would be appreciated.