There seems to be an increase in questions along the lines of "Is this a conflict of interest?" where the answer is "No." Is there, or should their be, a way to close these as duplicates?
Those questions are definitely rather different from each other, and there's no ground to close them as duplicates.
The only possibility I see would be that of creating a general, canonical Q&A about conflict of interest, covering the large majority of cases, and then closing those questions as duplicate of the canonical one. None of those questions have the necessary breadth to become the canonical one, and so we would have to create this from scratch.
I doubt there is a sufficiently strong interest in the community for a canonical Q&A on conflict of interest, but if you wish to draft one, you can then propose it on Meta.