Windows/Accessibility: NVDA sometimes reads out information twice

Repro steps:

1. Using any version of Qt that supports UI Automation, create a dialog with at least one button (see below code sample)
2. Open NVDA (https://github.com/nvaccess/nvda http://nvda.bhvd.de/ )
3. Show the dialog
4. Observe

Expected results:

• NVDA reads the dialog contents and the focused widget once (e.g. "Critical message dialog, This is a critical message, OK button, Enter")

Actual results:

• NVDA reads the dialog contents and the focused widget twice

Additional info:

• I am upgrading an application from 5.9.3 (MSAA accessibility backend) to 5.15.1 (UIA accessibility backend).  NVDA behaves as expected in 5.9.3.
• I only see this issue in Qt applications.  The UIA examples on MSDN do not exhibit this issue.
• Narrator does not exhibit this issue.  Only NVDA.
• The same issue can be seen when creating a simple dialog in Qt Designer and previewing it (from the Form menu)
• This might be related to QTBUG-90897, though the symptoms are slightly different.

Code sample:

#include <QApplication>
#include <QHBoxLayout>
#include <QMessageBox>
#include <QPushButton>

int main(int argc, char *argv[])
{
	QApplication app(argc, argv);
	QCoreApplication::setApplicationName("Qt NVDA double readout");

	QWidget window;
	window.resize({ 300, 100 });
	window.setLayout(new QHBoxLayout());

	QPushButton *button = new QPushButton("Click me!");
	QObject::connect(button, &QPushButton::clicked, []()
	{
		QMessageBox::critical(nullptr,
			"Critical message",
			"This is a critical message",
			QMessageBox::StandardButton::Ok);
	});
	window.layout()->addWidget(button);

	window.show();

	return app.exec();
}