message: [GUI] dashboard staking chart, prevent series added twice.
diff: @@ -449,8 +449,10 @@ void DashboardWidget::refreshChart(){
  set0->setColor(QColor(92,75,125));
  set1->setColor(QColor(176,136,255));
  - if(!series)
  + if(!series) {
  series = new QBarSeries();
  + chart->addSeries(series);
  + }
  series->attachAxis(axisX);
  series->attachAxis(axisY);
  @@ -513,7 +515,6 @@ void DashboardWidget::refreshChart(){
  series->append(set0);
  if(hasZpivStakes)
  series->append(set1);
  - chart->addSeries(series);
  // bar width
  if (chartShow == YEAR)
  