If you are very lucky, you might find that you have your hands on an original camera negative. This is easy to distinguish from a duplicate negative because it doesn't have any of the signs of having been produced by a printer. A step printer produces a darker or lighter frameline between the frames; a continuous printer produces a difference in density, sometimes very slight between the exposed parts (the transparent frameline) and the unexposed parts (for example, the borders and the edge areas between the perforations).
Original negatives have no border around the frame of any sort the edge densities between perforations is the same as the density between the frame lines. No "septum lines" of any sort - these are thin straight lines of density produced in a printer by masks and gate apertures of one sort or another not coinciding precisely and occur outside the frame area
If it is an edited negative it will have a splice between each shot. It is usually possible to identify non-edited material; these could be rushes that have not been edited yet.
In this case it essential to know if the film has never been finished; or if, on the contrary, it has been, then the non-edited material that you are identifying will most likely be rushes material that was never used and was termed negative out-takes.
Some laboratories use the term "cuts and trims" for cans of negative or rushes prints that have not been used in a production. It is not uncommon for producers to sell the cuts and trims to film stock shot libraries, after the editing is over, and cans containing several small rolls of scenes, original negatives and prints mixed up together in the same can will probably come from a commercial company such as this. This library material is often well used!
Sometimes cuts and trims are in loose rolls in which the individual lengths are not joined but simply interleaved in to make, what is sometimes called, a "peeled roll". This is done by both editors with rush print out-take, but also by negative cutting companies and laboratories during the negative cutting operation.
A peeled roll of negatives is a good sign that the material is probably negative out-takes and hasn't been touched since the production was made.