We have been running an instance of Vanilla forums for over a year. One of the things I would like to figure out is what to do with duplicate questions.
1. Link existing related posts
What I have been doing is copying date URLs from other posts to help answer questions. This works but I would prefer to get search results in front of users before they post because we already have answered many questions in our FAQ or other discussions and questions (and if we can get federated search up and working, our shopify product pages too!).
2. Avoid duplicates at post creation