\documentclass{article}

\usepackage[a4paper,pdftex]{geometry}
\usepackage{pdfpages}

\begin{document}

\includepdfmerge[nup=1x2]{DLIST.pdf,UniMelb.pdf}
\includepdfmerge[nup=1x2]{Nott.pdf,Otago.pdf}
\includepdfmerge[nup=1x2]{Rhodes.pdf,UTas.pdf}

\includepdfmerge[nup=1x2]{Hits.pdf,Cumulative.pdf}
\includepdfmerge[nup=1x2]{Normalised.pdf}

\end{document}
