Error if subfolder case doesn't match

[Giampaolo Fadel]

Win32, Mercurial 0.9.5:
If the working directory has a subfolder with mixed uppercase and 
lowercase characters in the name, when you refer to a file in this 
subfolder and you write the name of subfolder in different case 
Mercurial assume as a different file.
Example
The directory structure is:
C:\
    MyProject
        Sub                     (Subfolder of the project with mixed case)
            File1.txt

C:\MyProject>hg init
C:\MyProject>hg status
? Sub\File1.txt
C:\MyProject>hg add sub\*.txt                  (sub is lowercase)
C:\MyProject>hg status
A sub\File1.txt                                           (??? 2 files ???
? Sub\File1.txt                                           (???


Instead if I write the file name in different case it works right:

C:\MyProject>hg status
? Sub\File1.txt
C:\MyProject>hg add Sub\file*.*               (The case of subfolder is 
right but the case of file is wrong)
C:\MyProject>hg status
A Sub\File1.txt                                           (OK


Is it an error ? I'm a newbye on Mercurial! and may be that I don't 
understand many things.
Is it an already know error?
I looked in the bug tracker and mailing list, I found a lot of things 
concerning case and filename but no one refer to this precise error (or 
so I think).
Bye Paolo