Too many callbacks after installing multiple event handlers

Question

CoInitializeEx(NULL,COINIT_MULTITHREADED);
CoCreateInstance(CLSID_CUIAutomation, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pAutomation));
MyEventHandler* handler1 = new MyEventHandler();
MyEventHandler* handler2 = new MyEventHandler();
AnotherEventHandler* handler3 = new AnotherEventHandler();

pAutomation->AddStructureChangedEventHandler(element, TreeScope_Element, NULL, handler1 );
pAutomation->AddStructureChangedEventHandler(differentelement, TreeScope_Element, NULL, handler2 );
pAutomation->AddStructureChangedEventHandler(anotherelement, TreeScope_Element, NULL, handler3 );

Any events in any of the automation elements will trigger all event handlers callback functions

How do we avoid this?