====== How to overlay tow histograms and draw both stats boxes ======

void myfunction()
{
  ...
  TCanvas *c = new TCanvas(...)
  TH1D *h1 = new TH1D(...) ; // histo 1
  TH1D *h2 = new TH1D(...) ; // histo 2

  // set stats options (show histo title, nEntries, mean, rms)
  gStyle->SetOptStat(1111);

  // draw histo 1
  h1->Draw(); // draw histo and stats box on default position

  // get stats box
  gPad->Update(); 
  TPaveStats *statsbox = (TPaveStats*)gPad->GetPrimitive("stats");

  // get (default) y position of stats box (histo h1)
  double y1 = statsbox->GetY1NDC(); // (lower) y start position of stats box
  double y2 = statsbox->GetY2NDC(); // (upper) y start position of stats box

  // set new position of stats box (histo h1)
  double newy1 = 2 * y1 - y2;   // new (lower) y start position of stats box
  double newy2 = y1;            // new (upper) y start position of stats box
  statsbox->SetY1NDC(newy1);    //set new y start position
  statsbox->SetY2NDC(newy2);    //set new y end position

  // draw histo 2
  h2->Draw("sames"); // draw stats box on default position

  // Draw options:
  // "same"  : draw histogram on same canvas, do not redraw stats box
  // "sames" : draw histogram on same canvas, draw stats box (in default position)

 ...
}