Open directory - case insensitive

If i have a directory called IPupdate and i want to add another with the same path and name but i have the directory name in all lower case like this 'ipupdate' i get a message that this directory already exist. What i know it is possible to have one 'ipupdate' and one 'IPupdate' on Linux file system.
Why will it show me this message?

WinSCP 5.17.1

So I understand right, that the problem is not with opening/accessing that directory, but only with creating a bookmark to that directory?

Yes, the problem is that i can't create a bookmark.

OK, thanks for clarification. Indeed, the bookmarks are case insensitive. We will see if there's more demand for this change.

Very strange that you need votes for fixing this when we know that Linux file system is case sensitive. No one will ever bother to report or even find this page. Instead they will rename the folder. So here will never be any more demands to fix this.