You can use JavaScript to toggle the svg_2
on or off depending on its previous state (example using JQuery):
$("svg").click(function() {
if ( $('#svg_2').css('visibility') == 'hidden' )
$('#svg_2').css('visibility','visible');
else
$('#svg_2').css('visibility','hidden');
});
You could also use some other CSS attribute (such as display
).
See and try it here: JSFiddle