MWE:
\documentclass[referee]{svjour3}
\usepackage[english]{babel}
\begin{document}
\cite{yang2008,yang2010}
\bibliographystyle{IEEEtran}
\bibliography{IEEEabrv,bibfile_test}
\end{document}
The cls file can be obtained from here.
bibfile_test file:
@article{yang2010,
title={An analytical continuous-curvature path-smoothing algorithm},
author={Yang, Kwangjin and Sukkarieh, Salah},
journal={IEEE Transactions on Robotics},
volume={26},
number={3},
pages={561--568},
year={2010},
publisher={IEEE}
}
@inproceedings{yang2008,
title={3D smooth path planning for a UAV in cluttered natural environments},
author={Yang, Kwangjin and Sukkarieh, Salah},
booktitle={Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International Conference on},
pages={794--800},
year={2008},
organization={IEEE}
}
Resulting PDF:
Why do the authors disappear in the second case? How do I fix it (short of manually editing the bib file)?

---------. That's what theIEEEtranbibliography style is programmed to do with entries whose authors are repeated from the preceding entry. If you don't like this look, start looking for a different bibliography style. – Mico Feb 13 '18 at 15:26