BibTeX, biblatex and biber ⇒ Multiple Bibliography Entries by Author in one Year

[rawlins02]

I'm expecting the text to show (Romanovsky et al., 2010a, 2010b). Instead I'm seeing (Romanovsky et al., 2010a, b).

Here are the .bbl entries. Is something else controlling the behavior?

Code: Select all

\bibitem[{\textit{Romanovsky et~al.}(2010a)}]{Romanovsky:10}
Romanovsky, V.~E., S.~L. Smith, and H.~H. Christiansen (2010{\natexlab{a}}),
  {Permafrost thermal state in the polar Northern Hemisphere during the
  international polar year 2007--2009: a synthesis}, \textit{{Permafrost
  Periglacial Proc.}}, \textit{21}(2), 106--116, \doi{10.1002/ppp.689}.

\bibitem[{\textit{Romanovsky et~al.}(2010b)}]{Romanovsky2:10}
Romanovsky, V.~E., et~al. (2010{\natexlab{b}}), {Thermal state of permafrost
  in Russia}, \textit{{Permafrost Periglacial Proc.}}, \textit{21}(2),
  136--155, \doi{10.1002/ppp.683}.

[josephwright]

We will need to see more than a snippet: please construct a minimal example showing your LaTeX source.