[herendin2]

>The parent poster already addressed that

Thank you for your comment, but I don't agree

"telling the user that the username they typed exists, but they haven't offered the correct password for it" - is extremely different from Just telling the user 'wrong password'. It's different because it provides more information

>If you inform the user the username they typed exists, the chance of them not thinking about double-checking they didn’t mistype their own username increases.

That seems to be a user problem first of all, because it's based on the user's mistaken belief about the uniqueness of usernames. If possible, it would be best to help the user understand this.