One useful side-effect of this would be to stop people (accidently) voting-to-close the wrong part of the duplicate, something I've done a few times (I voted to close a duplicate, not realising that the other was already closed)
I have seen many useful information in "duplicate" posts. hayalci
Currently, if there is useful answers in the duplicate they basically disappear. They are really hard to find, even if you search:
- I've seen thematically identical questions asked with ZERO words in common. Last time I checked, Lucene wasn't magical faerie dust, unfortunately.. :) [source]
With proposed inverse-dupe links, you have a list of other very similar questions, which you can check for other useful answers if you're really interested in the question.
Perhaps the inverse-duplicates could be accessed by a link next to the edit/retag/flag/close, just below the tags? Something like..
Not sure about the wording, it's a bit long, but it seems to me a sensible place to put it..
Another two mockups, based on Shog9 and Ólafur's comments,
Image Dead - Duplicated by sidebar modification
Or, a slight variant on the current "Related questions" side bar, which lists (and highlights) exact duplicates:
Image dead: Related Questions sidebar with dupes highlighted
I quite like the last one - it's not as big of a change, doesn't much extra clutter (no new tabs/links under question), and is a sensible place - duplicates are "related questions" after all.