How can I close Suggestions for a good statistics book and a calculus book? as duplications both What are the recommended textbooks for introductory calculus? and Recommend a statistics fundamentals book?
A question can have more than one duplicate target. You can find some examples in this SEDE query.
As far as I remember:
- This happens if various users choose various duplicate targets when voting to close.
- And also if the list of duplicates is subsequently edited - this can be done by moderators or by user with a gold badge in the specific tag.
So to achieve this, you need either help from moderators or help from other users. So you could:
- Flag for moderators attention, and ask the mods to include multiple duplicates.
- An alternative could be to ask other users to help. So you could mention alternative duplicate targets in a comment when voting to close (or flagging as a duplicate) and/or you could ask the users in the chatroom called CURED to help with closures. (If some users notice this before the question is closed, they can choose another duplicate target when voting. And also if some user who can edit the list of duplicates notices it, they can change it also after the question is closed.)
Here is a post on Meta Stack Exchange when the possibility to edit the list of dupes was announced: Gold tag-badge holders and moderators can now edit duplicate links. There are also some feature requests like this one: Allow same user to add multiple links as possible duplicates.