You have to clear the queue:
$( ".c3_home" ).clearQueue().addClass('c3_left2').delay(400).queue(function(){
$(this).addClass('c3_right');
});
You could try using finish(): (jq 1.9 >) {which is supposed to clear all elements in queue}
$( ".c3_home" ).finish().addClass('c3_left2').delay(400).queue(function(){
$(this).addClass('c3_right');
});
As suggested by Kevin, try that too:
$( ".c3_home" ).addClass('c3_left2').delay(400).queue(function(next){
$(this).addClass('c3_right');
next();
});