Do you really need two similar rifles?
Yes! Look at all the guys with more than one break barrel springer!
If you are talking a new or any other Crosman-built Sheridan, it will not be better than the 140.
I don't have a 140, but I have a current model Benjamin 392 and Crosman 102 multi-pump repeater from the late '40's. Both are nice pump guns, but the Racine, Wisconsin built Sheridan was like the Cadillac of American airguns. On paper it may seem similar to other pumpers, but there is a mystique about a vintage Streak that is hard to explain. Mine wouldn't pump when I first saw it, but something about it "made" me want it.
After a valve job it is one of the best air rifles I have. If I had to go down to only one airgun, the Blue Streak would probably be the one.