For instance in the
Tamron fixed focal lengths lens database there are four entries for the Tamron SP 300mm f2.8 LD IF Adaptall2 Model 60b (and one for the 360b which is a legitimately different model). In this case this would be an easy fix 'cause there are three with no reviews submitted, and one with a review, so someone with the authority to do so could just delete the three extraneous ones. In other cases, there are multiple entries for a given model, each of which has a review or two (and sometimes mixing and matching lens reviews under the wrong models; see the Sigma 18-50/2.8 Macro/non-macro for such madness).
If it works for the moderators, I propose people could post in this thread to note duplicates, etc...