[turretslug]

Without formal data, one might (tenuously) infer that using B as the designation for "double diode" signifies that they were identical types designed to match closely in characteristics (e.g. for something that explicitly needed two matched diodes, such as a discriminator or other balanced use), whereas the separated AA might suggest two diodes that were not necessarily identical in characteristic, but that were perhaps more thoroughly screened from each other.

Straying a little from the original thread title, though.