[dredmorbius]

My practice is to usually limit "dupe" to the identical link or story submitted multiple times. Major mainstream breaking news possibly excepted.

For different takes on the same story, "Previously" with a link to earlier discussion, may be better.

For evergreen topics (e.g., Bertrand Russell's "In Defence of Idleness", submitted many times through the years, and again a day or so back), "earlier submissions" noting the years, of 2-3 top instances, can point to earlier interesting discussion.