If the intent is to make the stack a better Q&A
The question duplication link direction would better serve to direct visitors to the better answer. That means that the definition of "duplicate" is slightly different than the vernacular interpretation in that the earlier question could be a duplicate of a future thing. The temporal relationship then has dissonance with the usual meaning of duplicate.
Better Q&A is more useful
When I want a question answered or when I want to know the answer to a question, I'd like the best answer. Making that answer closer to the surface of the investigation is useful to the reader.
If the intent is to make the stack a history of questions and their answers
The duplicate question link should always point from more recent to more distant in time. The aim being to prevent a proliferation of repetitive answers to the repetative questions. Basically, record the acceptable and voted for answers for an OP's question and point to the history to avoid being drown by the noise of repeated questions.
Add a comment linking the two questions or answers
Solve the issue by adding a comment or question addendum linking to the more complete answer. That would side step the issue of using "duplicate" in an unconventional way.