# No disambiguation of same year, same author citations in biblatex-chicago author-date style while using option csmdate=both

I've been having trouble with the author-date style for biblatex-chicago, used with the option "csmdate=both". I use this option to provide "origyear" for some sources, but not for all. The problem seems to occur when I have 2 sources with identical authors and dates but no origdates. The following explains the problem.

I've added 2 references with identical dates and authors, but different titles and so on. When I cite them, biblatex-chicago does not differentiate between them. Where I would expect "Test 1935a" and "Test 1935b" I get two "Test 1935" but two separate entries in the reference list.

Any help is greatly appreciated.

Minimal working example:

\documentclass[utf8,12pt,letterpaper]{article}

\usepackage{setspace}
\usepackage[fallback]{xeCJK}

\usepackage{fontspec}
\defaultfontfeatures{Ligatures=TeX}

\newcommand{\mainfont}[0]{CMU Serif Roman}
\newcommand{\mainfontitalics}[0]{CMU Serif Italic}
\newcommand{\mainfontCJK}[0]{HAN NOM A}
\setmainfont[Ligatures={Common,TeX},Numbers={OldStyle},Contextuals=NoAlternate]{\mainfont}
\setCJKmainfont[Scale=0.9]{\mainfontCJK}
\setCJKfallbackfamilyfont{\CJKrmdefault}[Scale=0.9]{NanumMyeongjo}
\XeTeXlinebreaklocale "zh"
\XeTeXlinebreakskip = 0pt plus 1pt

\usepackage[authordate,strict,cmsdate=both,isbn=false,backend=biber,bibencoding=utf8,hyperref=true,annotation]{biblatex-chicago}

\title{}
\author{}
\date{}
\begin{document}
\maketitle

\cite{Test1}

\cite{Test2}

\printbibliography

\end{document}


Citing the following references:

@article{Test1,
author = {Test, T.},
title = {Random Title of Article One},
journal = {Journal},
volume = {20},
number = {3},
year = {1935},
pages = {1--46}
}

@article{Test2,
author = {Test, T.},
title = {Random Title of Article Two},
journal = {Journal},
volume = {20},
number = {4},
year = {1935},
pages = {50--70}
}


Replacing the "year" field with "date" makes no difference.

No clue why, but the citation style invokes \clearfield{extrayear} before printing the year label even when origyear is unavailable. Under cmsdate=both you can avoid this by adding the following to your preamble.

\makeatletter
% citations
\renewbibmacro*{cite:bothyear+oldstyle}{%
\iftoggle{cms@switchdates}
{\printtext[bibhyperref]{%
\bibopenparen%
\usebibmacro{cite:labelyear+extrayear}%
\bibcloseparen%
{\iffieldundef{origyear}
{\usebibmacro{cite:labelyear+extrayear}}% omit \clearfield{extrayear}
{\printtext[bibhyperref]{%
\bibopenparen%
\usebibmacro{origyear+endyear}%
\bibcloseparen%
\usebibmacro{cite:labelyear+extrayear}}}}}
% bibliography
\renewbibmacro*{bothyear+oldstyle}{%
\iftoggle{cms@switchdates}
{\printtext{%
\bibopenparen%
\usebibmacro{labelyear+extrayear}%
\bibcloseparen%
\clearfield{year}%
\clearfield{origyear}}%
{\iffieldundef{origyear}
{\usebibmacro{labelyear+extrayear}}% omit \clearfield{extrayear}
{\printtext{%
\bibopenparen%
\usebibmacro{origyear+endyear}%
\bibcloseparen%

You should contact the biblatex-chicago author directly to resolve this issue.