A question can be a duplicate of more than one question. Moderators and users with gold tag badges can add questions to the list of questions that a given question is a duplicate of. I was recently closing a question as a duplicate and I saw a lot of similar questions. This led me to wonder: Is there any limit to how many questions I can add to the list? Can I just keep on adding more questions forever, or will the system stop me at some point?
Can't find an official post on this, but the highest amount of dupe-targets I've encountered is five. I wrote a quick SEDE query sorting the posts by number of dupe targets coming from it, and this seems to confirm that "five" assumption.
SELECT pl.PostId AS [Post Link], COUNT(LinkTypeId) AS 'Number of dupe-targets' FROM PostLinks pl WHERE pl.LinkTypeId=3 GROUP BY pl.PostId ORDER BY 'Number of dupe-targets' DESC