Is this the way shadow_catch_only is supposed to work?

I'm having a problem with shadow-catch-only, which makes it virtually useless.  In the render, the object set to "Shadow catch only" disappears except for the shadow cast on its surface, as I'd expect, but the adjacent object also casts a shadow right through it, as if it weren't there. 

I want to see only the shadow cast on the object's surface.  I've tried multiple combinations of render engines and shadow types without success.

Does anyone know how (or if) this can be fixed?

Thanks