When I ask a question I do get a list of related questions that helps a lot to find out if my question has been asked before.
However I sometimes find an additional question that covers exactly the same topic in the list of related questions that only appears on the right after having posted the question. To avoid dupes I then need to delete my question.
It would be a nice feature to see this list at a time point before posting a question. This could also help new users to avoid posting dupes.