je crois que c'est vrai voici ce que j'ai trouvé sur un site, désolé c'est en anglais...
"Gibson often marked inferior quality guitars as "seconds", and sold them at a discount to dealers or employees. These markings were stamped into the wood on the back of the peghead. A "2" stamp is sometimes seen, designating a "second", which had some cosmetic flaw. If there is a serial number on the back of the peghead, the "2" is usually seen centered above or below it. Also sometimes stamped was "CULL", which is another designation of a second. Again, this stamp is seen on the back of the peghead. The worse Gibson reject is the "BGN" stamp, designating that instrument as a "bargin" guitar. These were only sold to employees at substantial discounts. This stamp is also seen on the back of the peghead. Sometimes the "BGN" is stamped vertically with the "N" below the "G" which is below the "B". BGN instruments weren't acceptable to Gibson as sellable to the public.
All second instruments are usually worth less than the same guitar that is not a second (given condition as the same). BGN instruments are worth less than a second instrument because these tend to have some fairly serious cosmetic flaw. "
