Geometry package arguments not doing anything

Question

For some reason in the following code, changing the margin argument for the geometry package line does nothing to the document. Even if I comment out the geometry package it doesn't go back to the defaults. I made sure I'm opening up the right PDF, I even deleted the pdf file to make sure I was opening up the correct PDF. I'm trying to get the space at the bottom of the page to be less (for some odd reason, it is way too much by default.)

 \documentclass[12pt]{article}
\usepackage[showframe=false,headheight=1cm]{geometry}
\usepackage{fancyhdr} % for headers and footers
\usepackage{lipsum}   % for dummy text
\usepackage{setspace}
\usepackage[margin=1in,bottom=1in]{geometry}

\begin{document}

% headers
\fancyhead[L]{}
\fancyhead[C]{}
\fancyhead[R]{
\begin{minipage}{2in}
 \raggedleft 
\small Derper McDerp \\
\small Derponomics 101 \\
\small Dr. Derpy Derp
\end{minipage}}
\renewcommand{\headrulewidth}{0pt}

% footers
%\fancyfoot[L]{}
%\fancyfoot[C]{}
%\fancyfoot[R]{}

% need to specify the pagestyle as fancy
\pagestyle{fancy}
\doublespace

\section*{Essay 3}
\lipsum
\end{document}

Anyone know what is going on with the geometry package?

Answer 1

Your MWE as is does not compile and results in

LaTeX Error: Option clash for package geometry.

But, loading the geometry package just once as:

\usepackage[showframe=true,headheight=1cm,margin=1in,bottom=1in]{geometry}

seems to work fine. Adjusting the setting bottom changes the margin as expected. For instance, using bottom=3in results in the following. I enabled showframe to see the effect.

As @egreg commented, the \geometry command can be used multiple times and the effects are cumulative. Perhaps you got confused with having multiple \geometry commands and the \usepackage options. So the following will yield the same results as above:

\usepackage{geometry}
\geometry{showframe=true,headheight=1cm}
\geometry{margin=1in,bottom=1in}