# OSCOLA BibLaTeX not recognizing repeated listing of author for co-authored works [duplicate]

This question follows from a previous question. I am using the OSCOLA BibLaTeX style file. In the bibliography, when citing the same author more than once, the author's name should be replaced with a double em-dash. This works except when the author has co-authored works. In that case, the first author name is printed in full.

This is a minimal working example. First, a .bib file:

@phdthesis{Author2002,  Author = {Author, An},  School = {Department of Something, University College Somewhere},   Title = {A PhD thesis}, Year = {2002}}

@article{Author2003,    Author = {Author, An}, Journal = {Some Journal}, Number = {2}, Pages = {163}, Title = {An Article},Volume = {27}, Year = {2003}}

@incollection{Author2009,   Author = {Author, An},  Booktitle = {Some Book},    Publisher = {Some Publisher}, Title = {Book Chapter}, Year = {2009}}

@article{Author2013,    Author = {Author, An and AnotherAuthor, An},Journal = {Another Journal},Number = {1},Pages = {55--69},Title = {Another Journal Article},    Volume = {45}, Year = {2013}}


And the .tex file:

\documentclass[12pt, a4paper]{article}
\usepackage[style=british]{csquotes}
\usepackage[style=oscola,   ibidtracker=true,          backend=biber,       autolang=hyphen]{biblatex}

% fixes a bug identified in a previous StackExchange question
\usepackage{xpatch}
\xpatchbibdriver{thesis}{\printnames{author}}{\usebibmacro{author}}{}{}
\title{Test Document}

\begin{document}
\maketitle
First citation.\autocite[66]{Author2013}
Second citation.\autocite[31--2]{Author2002}
Third citation.\autocite{Author2009}
\printbibliography[nottype=commentary,nottype=jurisdiction,nottype=legislation,nottype=misc,nottype=legal]
\end{document}


The bibliography looks like this, at least on my system:

Author A, ‘A PhD thesis’ (PhD thesis, Department of Something, University College Somewhere 2002).

— ‘Book Chapter’, in Some Book (Some Publisher 2009).

Author A and AnotherAuthor A, ‘Another Journal Article’ (2013) 45(1) Another Journal 55.

The last reference listed should start with — — and AnotherAuthor A. Does anyone have any idea how to fix this issue?