Crazy Input Behavior in IE9 & IE10

Crazy Input Behavior in IE9 & IE10

I'm using jQuery 2.0.2. I have a page with no forms, but multiple inputs all activated by jQuery. It's a pretty simple setup. The problem I'm having is that, if you type a number into a text input and hit return, that activates that input's "keypress" event, but then it also activates the "click" event on a completely different, unrelated button. It is completely wacky and makes no sense at all!

I made a very boiled down test case you can  check out here

Or for inline code, here is my HTML:
  1. <section class="double port_scan_box">
    <div>
    <h2>Server Port Test</h2>
    <p><input type="submit" value="Scan Ports" id="server_scan">
    </div>
    <div>
    <h2>Game Port Test</h2>
    <p><input type="submit" value="Scan Ports" id="game_scan">
    </div>
    </section>
    <section class="port_scan_box">
    <h2>Custom Port Test</h2>
    <p style="border: solid 2px yellow; width: 500px; margin: auto;">In IE9 and IE10, if you type a number into the field below and hit return/enter, you get redirected to the Server Port Test page, as if you had clicked the Scan Ports button on the top left!
    <p>In all other browsers, javascript turns the box below green, and no redirection takes place
    <p>Port Number: <input id="single_port" type="text" name="id" size="5" maxlength="5" class="input_class" autocomplete="off"> <input type="submit" value="Scan Port" id="single_scan">
    <div id="scan_results" class="scan_closed">Enter a port number above to scan</div>
    </section>


And here is my jQuery:

  1. $(function() {
    $("#server_scan").click(function(){ window.location.href = 'server/'; });
    $("#game_scan").click(function(){ window.location.href = 'games/'; });
    $("#single_scan").click( single_scanner );
    $("#single_port").keypress(function($e)
    {
    if ( $e.which === 13 )
    {
    single_scanner();
    //return false;
    $e.preventDefault();
    }
    });

    function single_scanner()
    {
    $("#scan_results").attr("class","scan_open").html("Port "+$port_number+" is Open");
    }
    });
And again to be clear, this only happens on IE9 and IE10. IE11 seems to function normally. All other non-IE browsers function normally. And IE8 and below are not supported by my site, or my version of jQuery. 

If you can figure out what is going on here, please let me know!