qmake: Potential name space clash without qmake's flat option?

qmake: problem when using CONFIG -= flat and CONFIG -= flat batch

If you have two files with the same name in different directories, and both files use the Q_OJECT macro, only one set of moc and object files are produced.

i.e.
foo.h
bar/foo.h

This confuses Visual Studio and the project won't build.