However, that still feels strange to me: when I use TH1D’s, the bins are not merged, and the number of labels in the axis increases; also, when I use the code I wrote, I get this info:
Info in <TH2F::Add>: Attempt to add histograms with different labels - trying to use TH1::Merge
which suggests it’s using Merge anyway, and so I would expect the two bins to stay separated.
But also, if I replace h1->Add(h2); with
auto mylist = new TList();
mylist->Add(h2);
h1->Merge(mylist);
(which is the actual way the docs suggest, and is what I’m trying to achieve) the result is still the same.