Looks like either you have a capital letter in your username and what I see is your username, or you don't have an emoji in your display name, or kbin strips emojis from usernames.
Edit: It appears kbin shows people's usernames, not their display names. That said, you still seem to have a capital letter in your username.
Like yours does? It just means he's commenting from another instance than your own home instance. If both you and the other are lemmy.world users and comment on a thread on a third instance, you shouldn't see it.