I am reviewing many posts with close votes recently, and I often end up with the same uneasiness about the reason to chose. In the "Community specific reason" option, there are
- This question does not appear to be about research level mathematics within the scope defined in the help center.
- MathOverflow is for mathematicians to ask each other questions about their research. See Math.StackExchange to ask general questions in mathematics.
I do not make sense of these two and don't understand why they coexist. Since it does not help the reviewers (at least not me), there should be a reason helping the OP to clarify the problem with his post.
Is there any reason to keep them both? If it would be only for me, I would merge them without hesitation.