In this article, I describe how to create a single A4-sized PDF document containing two copied of a single-page, A5-sized PDF document. This is useful for custom A5 forms that are to be printed in duplicate on A4 sheets, so that two A5 forms can be obtained by cutting the A4 paper.
This is a companion discussion topic for the original entry at https://www.xltoolbox.net/blog/2013/12/combining-two-a5-pages-into-one-a4-page.html