They partly have the same stories with the same names, but there are also stories they don’t share.
They are in the same folder and stories which are present in both feeds are only displayed once. This is actually quite nice, but as a side effect the stories that get suppressed are still unread when I finished reading the folder. So I have to open the folder twice to read them again, that is somewhat annoying.
I see there is a problem which path to choose, either display them all in the folder which makes for some redundancy (which I am fine with) or mark the duplicates automatically as read, which I would prefer. Of course that is bad if there are really different feeds with the exact same story names, but I don’t know how relevant that is. In either case, I think it would be better than the current solution.