Seems possible that the submitter account (puildupO) and the parent post's account (ClipNoteBook) are the same person? They reply to each other on their submissions, e.g. https://news.ycombinator.com/item?id=46433382 and https://news.ycombinator.com/item?id=46443460 and https://news.ycombinator.com/item?id=46414856 . We can also see in https://news.ycombinator.com/item?id=47383835 from the parent poster's account that the URL contains the submitter accounts username.