\documentclass{article}
\usepackage{multibib}
\newcites{multibiba}{bibA title}
\newcites{multibibb}{bibB title}
\begin{document}
Normal cite: \cite{ref}.
\bibliographystyle{alpha}
\bibliography{biblio.bib}

\bibliographystylemultibiba{plain}
\bibliographymultibiba{biblioa.bib}
Cite from bib A: \citemultibiba{refa}.

\bibliographystylemultibibb{alpha}
\bibliographymultibibb{bibliob.bib}
Cite from bib B: \citemultibibb{refb}.
\end{document}
