For your information, repeated threads or posts are not deleted solely based on the fact that something similar already exists because that isn't against the rules, however, it lowers the quality of your posts overall because no matter how good a post is, if it's repeated, you can't call it constructive because it has already been posted or discussed. For your posts or topics to be constructive or helpful, they need to be unique, most of the time, unless it is related to something that has been posted or discussed but is nowhere to be found anymore, maybe removed.

So, whenever you think of starting a thread, make sure you use the search function to see if you can't find something similar. If you do, don't do it, but if you don't, you can go ahead. The same goes for questions and confusions that you might have. There is nothing wrong in asking questions, but if you ask questions that are repeatedly asked and answered in other threads, it doesn't look good, you might even get criticism for it.