# Geometry package unexpected interaction with global twoside option and baselinestretch

The gif animation is obtained with the following tex code (by commenting out and restoring the corresponding parts of the preamble) and demonstrates that if twoside option is supplied as a global one (instead of a package option) then the lengths of marginparwidth and bottom change.

I am only interested in the latter one because this together with the baselinestretch change leads to a badbox error (Underfull \vbox).

Do you have any explanation for this phenomenon or an idea to fix it? I am preparing a thesis template for our university and being able to supply twoside, oneside as a global option has its benefits (especially in a thesis document with a separate template file), otherwise the user needs to locate where the geometry package is loaded and modify the template file.

% \documentclass[12pt, a5paper]{report}
% \usepackage[margin=2.5cm, bindingoffset=1cm, heightrounded, showframe]{geometry}

% \documentclass[12pt, a5paper]{report}
% \usepackage[margin=2.5cm, bindingoffset=1cm, heightrounded, showframe, asymmetric]{geometry}

% \documentclass[12pt, a5paper]{report}
% \usepackage[margin=2.5cm, bindingoffset=1cm, heightrounded, showframe, twoside]{geometry}

% \documentclass[12pt, a5paper, oneside]{report}
% \usepackage[margin=2.5cm, bindingoffset=1cm, heightrounded, showframe]{geometry}

% \documentclass[12pt, a5paper, asymmetric]{report}
% \usepackage[margin=2.5cm, bindingoffset=1cm, heightrounded, showframe]{geometry}

\documentclass[12pt, a5paper, twoside]{report}
\usepackage[margin=2.5cm, bindingoffset=1cm, heightrounded, showframe]{geometry}

\usepackage{lipsum}

\renewcommand{\baselinestretch}{1.5}

\begin{document}