I've run across some of those recently too: Gedcom imports that created duplicates of multi-generation families, with names and dates identical to the names and dates on the existing profiles.
We do have to assume good intentions. When I propose merges for those duplicates, my comment often includes an observation that the duplication should have been apparent when the new profile was created. Sometimes that generates a message of explanation and apology from the profile creator, and even if they don't reply that way, I think that it usually helps induce members to be more careful in the future. You also could send a note to the profile creator asking if they can explain how they happened to create those duplicates, because you want to see if WikiTree should make improvements to prevent those mistakes in the future.
And if the dimensions of the situation exceed what you are willing to try to deal with, see Help:Problems with Members