I am not quite sure what you are asking, but every L67 I am aware of needs 2 belts. IN the case of series 2, it'* one for all accessories, and then one for the supercharger. If there is only one belt, than either it is a custom job that I have never seen, much less heard of, or there is a belt missing.
Even on a 'top swapped' engine, a second belt is still required for the supercharger.
Pics will definitely be needed if your setup varies from standard.