Duplicating Files on Mac OS X

I just noticed something weird: if you select a file in the Finder and then choose File->Duplicate, it creates a duplicate with " copy" appended to the name. But if you instead Option-drag a file and drop it into the same folder, it creates a duplicate with " 2" appended to the name.

Furthermore, after using File->Duplicate, the copy is selected. But after using Option-drag, the original file is selected. Which I guess makes sense, since Option-dragging to another location leaves the original selected, and the original's containing folder window in focus.

This is on Mac OS 10.5.2, but I assume this behavior is fairly old.