syndication_search looks through the project's questions and answers, and syndication_ask itself compares a new question with the open questions, the current answers, the Planning, the Rules, the project's decisions and failed approaches and its knowledge. When it finds a strong match it creates nothing and returns POSSIBLE_EXISTING_ANSWER with the matches; the agent reads them and, only if none answers it, asks again with force_new and a reason.
The match is by words, not by meaning: SyncNow compares the significant words of the question, rarer words weighing more, so a question written with other words may not be found, and shared words do not prove it is the same question. An answer marked as possibly outdated is not offered as an existing answer.
The team is never stopped this way: a question you ask in the app is always created, and similar questions found by the same word matching are listed under it. The same team member, or the same agent session, sending the same subject and text again within 24 hours gets the existing question back instead of a duplicate, unless a question asked in the app carries attachments: then it is a new question, so that its files are not lost. See What limits apply to project questions, and how are loops avoided?.