How to respond to a comment when two reviewers ask the same or similar question?
This is very common and there's no need to overthink it.  Answer the question for Reviewer 1, and then when listing and answering Reviewer 2 questions, write out the question and answer "This is the same point as question 3 from Reviewer 1, and is addressed in my response there."

You should be very sure you've addressed the question clearly and thoroughly, because if multiple reviewers flag it then there's some problem you need to sort out.