Many questions here on PSE are in the form of a straightforward riddle. I'm not talking about more complex puzzles which have a riddle element as well as many other parts to them, but just about puzzles which consist of a single riddle, with a single solution, and nothing else.
When should two such puzzles be considered duplicates?
I had a quick look through some of the existing duplicate riddles. There are many which have the solution NOTHING and have been closed as duplicates of Oh, it is greater than God! despite not having quite the same wording (examples: one, two, etc.) Then there are some which have the solution COFFIN and have been closed as duplicates of Riddle of the Unwanted Present (examples: one, two, etc.) Both of these are old 'chestnut' riddles, which explains why they appear so often.
On the other hand, there are riddles which have the same answer and reasonably similar clues but haven't been closed as duplicates: for instance, I'm 26, what am I? - riddle and the earlier An easy riddle, for once. I'm a hot girl! I don't remember whether I VTCed this one or just commented with a link to the previous question, but in any case it was never closed. Perhaps it should have been?
Let's try to make some reasonably clear guidelines for when to dupe-close riddles.
I'm very close to getting a gold tag badge for riddle, which is why I'd like to have a clear policy on this. If there's a community consensus on when riddles should be considered duplicates, then I'm less likely to be accused of abusing my dupehammer powers.