Recently in the main site, I visited the users tab, and there I searched for "Subhadeep Dey", and it showed two results, this one and my own profile, and in both the cases, the username is totally same.
Though the other user has not participated in the site (just made an edit in Stack Overflow), and as an user, he is older than me; but in future, suppose he becomes a noteworthy member, then if other users ping "@SubhadeepDey", who will be informed as the "response"?