<p>A question can be closed as a duplicate of two others if different users voting to close pick different duplicates (<a href="https://stats.stackexchange.com/questions/258820">a recent example</a>), but a single user can't pick more than one. Leaving a comment linking to a second duplicate is good enough&mdash;it <em>could</em> be deleted, but won't be. Links to both will appear 'Linked' list on the right of the page.</p>

<p>In some cases, especially when <em>A</em> isn't asked as "<em>B</em>? and <em>C</em>?", a "stub" answer may be a good idea: one that disentangles the issues &amp; explains how the linked duplicates address them. In others there may be some mileage in a "compare &amp; contrast"-type answer.</p>
