The second call will open the event, it will not change the event's state.
I know this because the documentation says that it opens it but not that it resets it. If it reset it, that would be important enough to mention.
HANDLE responseWaitEvent = CreateEvent(NULL, // no security
TRUE, // manual-reset event
TRUE, // signaled
(LPTSTR)_T("TESTEvent")); // event name
assert(responseWaitEvent && "Could not create event");
responseWaitEvent = CreateEvent(NULL, // no security
TRUE, // manual-reset event
FALSE, // not signaled
(LPTSTR)_T("TESTEvent")); // event name
assert(responseWaitEvent && "Could not open event");
DWORD dw = WaitForSingleObjectEx(responseWaitEvent, 10000, FALSE);
assert(dw != WAIT_TIMEOUT);
And the opposite:
HANDLE responseWaitEvent2 = CreateEvent(NULL, // no security
TRUE, // manual-reset event
FALSE, // not signaled
(LPTSTR)_T("TESTEvent2")); // event name
assert(responseWaitEvent && "Could not create event");
responseWaitEvent2 = CreateEvent(NULL, // no security
TRUE, // manual-reset event
TRUE, // signaled
(LPTSTR)_T("TESTEvent2")); // event name
assert(responseWaitEvent && "Could not open event");
DWORD dw2 = WaitForSingleObjectEx(responseWaitEvent2, 10000, FALSE);
assert(dw2 == WAIT_TIMEOUT);