dumpcpp uses "-n" option value for guard macros in headers which is wrong because that implies that every QtAx COM wrapper must have a unique namespace so that one cpp file could include several headers at same time. File names should be used for include guards.

My paritcular case is using OPOS device drivers which are located in its own file by device type plus one common file with constants, like this:

Opos_Constants.dll 
OPOSPointCardRW.ocx 
OPOSPOSKeyboard.ocx 
OPOSPOSPower.ocx 
OPOSPOSPrinter.ocx 
OPOSRFIDScanner.ocx 
... 

It's natural that they all should get in the same C++ namespace and at least two files (constants and any other driver) are included simultaneously.

dumpcpp OPOS\CommonCO\OPOSBelt.ocx -n OPOS -o OPOS\QtWrappers\Belt 
dumpcpp OPOS\CommonCO\OPOSBillAcceptor.ocx -n OPOS -o OPOS\QtWrappers\BillAcceptor 
dumpcpp OPOS\CommonCO\OPOSBillDispenser.ocx -n OPOS -o OPOS\QtWrappers\BillDispenser 

and every header has this:

/**************************************************************************** 
** 
** Namespace OPOS generated by dumpcpp from type library 
** OPOS\CommonCO\OPOSBelt.ocx 
** 
****************************************************************************/ 

#ifndef QAX_DUMPCPP_OPOS_H 
#define QAX_DUMPCPP_OPOS_H 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ wrong