If you have a C++ project that has a bunch of .ODL files and the generated .h files from the ODL compiler, should doxygen be told to parse both .odl and .h, or only one or the other? In general I don't like documenting generated code but IDL is sort of a special case.
In any case, it seems like the member listing of ODL files is not quite working properly in my tests, are ODL files properly parsed?
From this page it seems the Doxygen perfectly supports parsing *idl and *.odl files. Maybe you have some issues regarding the comments format ?
Anyway, I would advise you against parsing both *.idl/*.odl files and generated .h files. The latter are, by definition, generated and represent the same classes than the one defined in the *.idl/*.old files.
Parsing both is like documenting the same set of classes twice, which is obviously not a good idea.