i am guessing it is because of:

Qt Code:
  1. ui_pushButton_START = qFindChild<QPushButton*>(this, "pushButton_START");
  2. ui_pushButton_Select = qFindChild<QPushButton*>(this, "pushButton_Select");
  3. ui_pushButton_Recombine = qFindChild<QPushButton*>(this, "pushButton_Recombine");
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i think it's causing connectSlotsByName to connect the signal/slot for each button twice because you have an aditional pointer ...
i may be wrong though...