Do photocopies have a “value of zero”?

As a laboratory (www.makrisforensics.gr) we have recently dealt with two [2] cases that had photocopies as disputed evidence, in one case photocopies of cheques (of non-verified "generation" and without certification of the authenticity of the photocopy) and in the other case photocopies of many -draft- pages with handwritten notes and numerical amounts, where -in both cases- their authenticity had to be verified.