http://bugs.winehq.org/show_bug.cgi?id=28213
--- Comment #6 from A Wine user RandomAccountName@mail.com 2012-04-21 19:52:34 CDT --- (In reply to comment #5)
You could make a short test on Windows to check if it really asks for overwrite on existing file when invoked through "cmd.exe /c copy ..." (vs. "copy ...").
Windows 7 simply overwrites the target file without asking.
Thanks for the analysis and better workaround. :)