Added a warning against using twoside,printed and oneside,digital.

guide/mu/guide.dtx

@@ -410,6 +410,13 @@
       typesetting is generally regarded as more visually pleasing
       and double-sided printing consumes less paper. Use at least
       120 grams per square meter paper to prevent show-through.
+
+      \emph{You may feel compelled to use \thguide@itemfmt{twoside}
+      for the printed version of the thesis and \thguide@itemfmt{%
+      oneside} for the digital version to reduce the number of
+      blank pages. This will, however, cause the page numbers to
+      differ between the printed and the digital version, which
+      will make it difficult to cite your work. Do not do it.}
     \item[\thguide@default onecolumn]
       This option causes the main text of the thesis to be set in
       one column.