Can I create a view that shows duplicated tickets?
It's not possible to have a view that shows duplicated tickets. However, in any view, you can add the Requester column if it is not yet present. Then, click the Requester title to order the tickets. This allows you to quickly see which tickets belong to the same requester and proceed with merging them if they turn out to be duplicated.
For more information, see this article: Creating views to manage ticket workflow.