Originally, when we entered duplicate/similar titles for content/articles/cases, we would get notified that it may be a duplicate article. However, we're no longer getting that. I've attached a screen shot of the action set that is currently in place. There aren't any conditions for it, maybe there's supposed to be?
I would recommend logging a Service Request with Pega Global Customer Support (GCS), as we may need to look at tracer files or other logs to help determine why the duplicate check is no longer functioning in your env. Pls note that the duplicate check feature is only triggered during the initial creation of the article, not when editing previously-published articles.