Line spacing not matching on second page of two-column checklist

Question

I'm trying to make a half-sheet (letter-size paper) checklist with two columns using LaTeX. I set the page size to 8.5x5.5 inches, used fancyheader to put the title at the top of pages, defined a checklist environment, and set \twocolumn.

Then I put the checklist section itself in \foreach \n in {1,2} to print two half-sheets into the output file. Then I'll use my pdf viewer to print two pages/sheet.

This all works great, except for the fact that the line spacing is off on the second page. The first page is perfect, but on the second page (which I'd expect to be the same), the second column has slightly smaller line spacing than the first, which leads to it being significantly off by the bottom of the page. Why is this happening?

Here's a link to my output, if it'd be easier than compiling the document: http://thetechnicalgeekery.com/downloads/temp/checklist.pdf

\documentclass[12pt]{article}

% size
\usepackage{geometry}
\geometry{papersize={8.5in, 5.5in}}
\geometry{margin=1in}

% checkbox list
\usepackage{latexsym}
\newenvironment{checklist}{
  \begin{list}{}{}
  \let\olditem\item
  \renewcommand\item{\olditem[$\Box$] }
  }{
  \end{list}
}

% title
\newcommand{\doctitle}{Checklist}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}
\fancyhead[RO,RE]{\LARGE \doctitle \normalsize}

% other stuff
\usepackage{tikz}
\twocolumn

\begin{document}
\foreach \n in {1,2} { % print 2 copies for 2 to a page

\begin{checklist}
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\end{checklist}
} % foreach

\end{document}

Answer 1

Using egreg's suggestion and adding \noindent and \newpage to every spin of the loop you can get identical pages. For that I've divided the list into two but it doesn't matter.

\documentclass[12pt]{article}

% size
\usepackage{geometry}
\geometry{papersize={8.5in, 5.5in},headheight=19pt}
\geometry{margin=1in}

% checkbox list
\usepackage{latexsym}

% title
\newcommand{\doctitle}{Checklist}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}
\fancyhead[RO,RE]{\LARGE \doctitle \normalsize}

% other stuff
\usepackage{pgffor,pgfmath}

\begin{document}\twocolumn
\foreach \n in {1,...,4} {
\noindent\begin{itemize}
\renewcommand\labelitemi{$\Box$}
\foreach \x[evaluate=\x as \y using {int(Mod(\x,2)+1)}] in {0,...,9}{
\item Item \y
}
\end{itemize}\newpage
}
\end{document}

---

EDIT : It turns out that the result of the multicol structure was sought.

\documentclass[12pt]{article}
% size
\usepackage{geometry}
\geometry{papersize={8.5in, 5.5in}}
\geometry{margin=1in}
% checkbox list
\usepackage{latexsym}
\newenvironment{checklist}{
  \begin{list}{}{}
  \let\olditem\item
  \renewcommand\item{\olditem[$\Box$] }
  }{
  \end{list}
}
% title
\newcommand{\doctitle}{Checklist}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}
\lhead
\chead
\rhead{\LARGE \doctitle \normalsize}
% other stuff
\usepackage{pgffor,pgfmath,multicol}
\begin{document}
\begin{multicols}{2}
\foreach \n in {1,2} { % print 2 copies for 2 to a page
\begin{checklist}
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\item Item 1
\item Item 2
\end{checklist}
} % foreach
\end{multicols}
\end{document}