1826 2-B/4-D are both the same variety from the Stone family. There are 7 varieties documented in this family, and this variety appears to be the most common (relatively speaking), although fewer than 10 examples of this variety have been doucmented.
 
This example is about as nice as I've seen compared to the photographed population. The silvering was thick enough to remain uniform across the surfaces. There's an odd yellow oxidation across the surface and some green verdegris that might be able to be removed.