https://bugs.winehq.org/show_bug.cgi?id=29081
--- Comment #11 from Damjan Jovanovic damjan.jov@gmail.com --- It's possible that some apps accept both OLE drag and drag and WM_DROPFILES, and since we do both, the files appear to be dropped twice :-).
Maybe we shouldn't send WM_DROPFILES if the files were successfully dropped via OLE first? Let me see if I can make a quick patch for you to try.