title: Removing Duplicate Entries in a ROOT TTree
body: <p>I have three <code>.root</code> files that I need to merge together. Normally I would use <code>hadd</code> to merge the files, but the files contain duplicate entries which I need to remove. I can't just delete the duplicated entries because TTrees are read-only. Is there a simple way to merge the files while ensuring that only unique entries are saved?</p>