Graig and list, My take on the additional stamping of the BB on Pogliaghi's is to ID a specific frame from a standard production bike. I have 5 Pogliaghi's. Only one of them has an additional stamp. It's SN# 9452 purchased in around 1970 from Velo Sport Cyclery. The BB is stamped with a VSC. This seams to be in aline with other stampings on Pogliaghi BB shells.
Brian Fessenden
Orinda, CA