With ActiveState Perl and windows you have case insensitive filesystem and also both slash and backslash work for path separator.

C:\>perldoc -l IO::Socket IO::socket CGI
C:\Perl\lib\IO\Socket.pm
C:\Perl\lib\IO\socket.pm
C:\Perl\lib\CGI.pm
[download]

Are you using cygwin? It has also similar methods to ensure unix programs work.

-- regards, Roman