--replace             replace object if already existing

rm copy.root
rootcp -r --replace tutorials/hsimple.root copy.root;
root.exe -b -l copy.root -e 'gFile->ls()' -q
rootcp -r --replace tutorials/hsimple.root copy.root; 
root.exe -b -l copy.root -e 'gFile->ls()' -q

pcanal@Viroflay:~/root_working/build/master-debug$ rm copy.root 
pcanal@Viroflay:~/root_working/build/master-debug$ rootcp -r --replace tutorials/hsimple.root copy.root; root.exe -b -l copy.root -e 'gFile->ls()' -q

Attaching file copy.root as _file0...
(TFile *) 0x5645f4423530
TFile**         copy.root
 TFile*         copy.root
  KEY: TH1F     hpx;1   This is the px distribution
  KEY: TH2F     hpxpy;1 py vs px
  KEY: TProfile hprof;1 Profile of pz versus px
  KEY: TNtuple  ntuple;1        Demo ntuple
pcanal@Viroflay:~/root_working/build/master-debug$ rootcp -r --replace tutorials/hsimple.root copy.root; root.exe -b -l copy.root -e 'gFile->ls()' -q

Attaching file copy.root as _file0...
(TFile *) 0x55f09c1bbc50
TFile**         copy.root
 TFile*         copy.root
  KEY: TH1F     hpx;2   This is the px distribution [current cycle]
  KEY: TH1F     hpx;1   This is the px distribution [backup cycle]
  KEY: TH2F     hpxpy;2 py vs px [current cycle]
  KEY: TH2F     hpxpy;1 py vs px [backup cycle]
  KEY: TProfile hprof;2 Profile of pz versus px [current cycle]
  KEY: TProfile hprof;1 Profile of pz versus px [backup cycle]
  KEY: TNtuple  ntuple;1        Demo ntuple