How to get the option 'globalcitecopy' of bibunits with biblatex?

Question

I've just changed from natbib + bibunits to biblatex and I'd like to get the functionality of the globalcitecopy option. As explained in the documentation of bibunits:

Create an entry in the global bibliography for each cite command within a bibunit. Default is to create an entry only for the local bibliography.

I've defined refsectionswith biblatex, but when trying to print the global bibliography either with \printbibliography or \bibbysection I can't get all the references cited in the whole document shown and sorted all together.

After reading the documentation of biblatex I suppose I'm skipping something, but I can't guess. How should it be done?

---

As @moewe pointed out, I was mixing concepts. Just using segments instead of sections solves it.

\documentclass[a4paper,titlepage,10pt,twoside,openright]{report}

\usepackage[backend=biber,style=ieee-alphabetic,natbib=true]{biblatex}
\addbibresource{IEEEfull.bib}
\addbibresource{IEEEexample.bib}

\usepackage{lipsum}

\begin{document}

%\begin{refsection}
\begin{refsegment}
 \chapter{Introduction}
 \cite{IEEEexample:articledualmonths}
 \section{First section}
 \cite{IEEEexample:shellCTANpage}

 %\printbibliography[heading=subbibliography]
 \printbibliography[segment=\therefsegment,heading=subbibliography]
%\end{refsection}
\end{refsegment}

\section{Second section}
\cite{IEEEexample:IEEEwebsite}
\nocite{IEEEexample:book_typical,IEEEexample:article_typical}  

\cleardoublepage

\printbibliography[heading=bibliography]

\end{document}