MWE
\documentclass[a4paper,11pt]{book}
\usepackage{multicol}
\usepackage{titletoc}
\makeatletter
\renewcommand{\tableofcontents}[1][\contentsname]{%
\section*{#1}
\begin{multicols}{2}
\@starttoc{toc}
\end{multicols}
}
\makeatother
\begin{document}
\part{ONE}
\tableofcontents
\chapter{One}
\section{1-One}
\part{TWO}
\tableofcontents % <--- empty page
\chapter{One}
\section{1-One}
\end{document}
How do I print the contents page on another page?

etocpackage. From the description: "The\tableofcontentscommand may be used arbitrarily many times in the same document, while\localtableofcontentsprovides a 'local' table of contents." – Werner Aug 29 '19 at 21:08\tableofcontentsto print. You could print two duplicate\tableofcontents', but it seems like you want something specific to each\part. See How can I print the table of contents multiple times in my document? – Werner Aug 29 '19 at 21:21\tableofcontentsto be the same in both cases? – Werner Aug 30 '19 at 17:44