I have asked the question OS X: Blurry Beamer presentations on Sierra / High Sierra, which is about workarounds for the broken PDF rendering on recent versions of OS X that bite especially those of us, who are presenting with LaTeX
A few days later (spotted by user samcarter) the question What PDF Viewer can be used to present slides on High Sierra? appeared on Ask Different (the Apple users SE site), which is about the very same problem and setting and, thus, would qualify as a duplicate.
As a helpful action for others seeking for advice, I had duplicated the answer of user DG' to Ask Different and linked to the original. However, such kind of redundancy is generally discouraged at SE sites. On the other hand, both, the question and the answer (arguably) fits the scope of both sites.
So how to handle cross-site dupes? If either one gets removed, will there be the common "duplicate" box pointing to the related question on the other site?