Spencer, Guilford, Conn
Smith's & Bertoia's books list this as a doorstop and the reason, it is shown here.
Notice this Doorstop has a flat protrusion extending from its back.
This protrusion is designed for sitting under books for stability purposes.
This is typical of a lot of bookends--See the "Doorstop Information" section on Home Page
Second, its height is very short (4 inches) typical of a Bookends and not a doorstop.
Thus, this casting is considered a "Bookend" by this website.