In the following document, I am using \titleGM for a custom title page, from the titlepages collection. This results in a page number (in Roman numerals) on the backside of the title page. However, if I replace the custom \titleGM with \maketitle, then there is no page number on the backside.
Note that page numbering correctly restarts from i for the Table of Contents even with the custom title page.
How do I remove the page numbering from the backside of the custom title page?
\documentclass{memoir}
\usepackage[T1]{fontenc}
\input{titleGM.tex}
\usepackage{blindtext}
% https://tex.stackexchange.com/a/37396/2113
% Just to have a long enough ToC to see its page numbers
\usepackage{forloop}
\newcounter{loopcntr}
\newcommand{\rpt}[2][1]{%
\forloop{loopcntr}{0}{\value{loopcntr}<#1}{#2}%
}
\title{Retrocomputing with Clash}
\author{Gergő Érdi}
\date{}
\begin{document}
\frontmatter
\begin{titlingpage}
\titleGM
%% \maketitle
\end{titlingpage}
\tableofcontents
\mainmatter
\rpt[30]{\chapter{Foo}\Blindtext}
\backmatter
\end{document}

