SetOverwrite ifdiff fails with FAT

SetOverwrite ifdiff bug under Win9x.

Step to reproduce:
-Make an installer that install at least 1 file.
-Install on a clean WinME(or 9x) machine.
-Reinstall the same software(always using SetOverwrite
ifdiff)

Result: The file is replaced and if the file was locked,
the error flag is set.

Expected: The file is skiped because it is the same.

I know that the low dword part of function GetFileTime
did not return the same value under Win9x than WinXP.
Maybe this is the same problem.

I'm using NSIS v2.0