title: pyQt: radioButton.isChecked() is executed twice
body: <p>I have this simple window <em>(design.py)</em> derived from Qt designer, which consists of three radio buttons:</p>
  
  <pre><code># -*- coding: utf-8 -*-
  
  from PyQt4 import QtCore, QtGui
  
  try:
      _fromUtf8 = QtCore.QString.fromUtf8
  except AttributeError:
      def _fromUtf8(s):
          return s
  
  try:
      _encoding = QtGui.QApplication.UnicodeUTF8
      def _translate(context, text, disambig):
          return QtGui.QApplication.translate(context, text, disambig, _encoding)
  except AttributeError:
      def _translate(context, text, disambig):
          return QtGui.QApplication.translate(context, text, disambig)
  
  class Ui_MainWindow(object):
      def setupUi(self, MainWindow):
          MainWindow.setObjectName(_fromUtf8("MainWindow"))
          MainWindow.setEnabled(True)
          MainWindow.resize(158, 110)
          self.centralwidget = QtGui.QWidget(MainWindow)
          self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
          self.myradioButton1 = QtGui.QRadioButton(self.centralwidget)
          self.myradioButton1.setGeometry(QtCore.QRect(20, 10, 102, 22))
          self.myradioButton1.setObjectName(_fromUtf8("myradioButton1"))
          self.myradioButton2 = QtGui.QRadioButton(self.centralwidget)
          self.myradioButton2.setGeometry(QtCore.QRect(20, 40, 102, 22))
          self.myradioButton2.setObjectName(_fromUtf8("myradioButton2"))
          self.myradioButton3 = QtGui.QRadioButton(self.centralwidget)
          self.myradioButton3.setGeometry(QtCore.QRect(20, 70, 102, 22))
          self.myradioButton3.setObjectName(_fromUtf8("myradioButton3"))
          MainWindow.setCentralWidget(self.centralwidget)
          self.statusbar = QtGui.QStatusBar(MainWindow)
          self.statusbar.setObjectName(_fromUtf8("statusbar"))
          MainWindow.setStatusBar(self.statusbar)
  
          self.retranslateUi(MainWindow)
          QtCore.QMetaObject.connectSlotsByName(MainWindow)
  
      def retranslateUi(self, MainWindow):
          MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow", None))
          self.myradioButton1.setText(_translate("MainWindow", "RadioButton1", None))
          self.myradioButton2.setText(_translate("MainWindow", "RadioButton2", None))
          self.myradioButton3.setText(_translate("MainWindow", "RadioButton3", None))
  </code></pre>
  
  <p>and I have added this code, in order to monitor which radio button is checked.</p>
  
  <pre><code># -*- coding: utf-8 -*-
  
  from PyQt4 import QtGui, QtCore
  import sys
  import design
  
  class ExampleApp(QtGui.QMainWindow, design.Ui_MainWindow):
      def __init__(self, parent=None):
          super(ExampleApp, self).__init__(parent)
          self.setupUi(self)
  
          self.myradioButton1.toggled.connect(self.myradioButton1_function) 
          self.myradioButton2.toggled.connect(self.myradioButton1_function) 
          self.myradioButton3.toggled.connect(self.myradioButton1_function) 
  
      def myradioButton1_function(self):
          if self.myradioButton1.isChecked():
              print 'myradioButton1 is Checked'        
          if self.myradioButton2.isChecked():
              print 'myradioButton2 is Checked'        
          if self.myradioButton3.isChecked():
              print 'myradioButton3 is Checked'        
  
  def main():
      app = QtGui.QApplication(sys.argv)
      form = ExampleApp()
      form.show()
      app.exec_()        
  
  if __name__ == '__main__':
      main()    
  </code></pre>
  
  <p>I noticed that if radioButton1 is checked, it seems to work fine, but if radiobutton2 or radiobutton3 are checked, the check message is printed twice.</p>
  
  <p>On the other hand, if I connect every signal to a different function, like this:</p>
  
  <pre><code>class ExampleApp(QtGui.QMainWindow, design.Ui_MainWindow):
      def __init__(self, parent=None):
          super(ExampleApp, self).__init__(parent)
          self.setupUi(self)
  
          self.myradioButton1.toggled.connect(self.myradioButton1_function) 
          self.myradioButton2.toggled.connect(self.myradioButton2_function) 
          self.myradioButton3.toggled.connect(self.myradioButton3_function) 
  
      def myradioButton1_function(self):
          if self.myradioButton1.isChecked():
              print 'myradioButton1 is Checked'   
  
      def myradioButton2_function(self):
          if self.myradioButton2.isChecked():
              print 'myradioButton2 is Checked' 
  
      def myradioButton3_function(self):
          if self.myradioButton3.isChecked():
              print 'myradioButton3 is Checked'
  </code></pre>
  
  <p>then it works as expected.</p>
  
  <p>So, I guess that the trouble occurs when I want to connect many signal to one function. Could someone explain this behavior?</p>
  
  <p>Any thoughts would be appreciated.</p>