Ok I understand that but say they are different species wouldnt a collection point be a sure fire way to ID which one you got? I've noticed alot of pleco's have multiple L#'s Like P. gibbiceps as you stated and even P. joselimaianus. Thats what im getting at. From what I read when there adults there are several differences between the two (L114 and L600).
Not if the natural ranges overlap one another. The type specimen for P.leopardus (L600) is from Guyana, majority of L114 come from Rio Demini in Brazil, however they're both found in tributaries of the Rio Negro in Brazil. Under normal circumstances, catch local is one of the better ways to id fish. You do need to be aware of the method by which fish are collected & sold on the Amazon however. Natives catch fish and transport them downstream to awaiting vessels where they are sold and placed into captivity with other fish purchased in a similar method. These vessels then sail further downstream, collecting fish along the way, until the reach one of the major export hubs on the Amazon. Here they are collected at exporters until shipped out. Thus, it can be very difficult to get an accurate catch local. Some fish can even be caught in one country & exported from another.
L114 & L600 do have distiguishing features when adults, but only as adults. Thus the reason I posted in my original post that at the size of you fish it can be impossible to distinguish between L600 & L114. If I were a betting man however I'd say I was about 99% sure its L114.