duplicate form

The form is duplicated, I use functions.php theme to insert the tags, the error has occurred after the last update, sample page
function.php

function add_post_content($content) {
	if(!is_feed() && !is_home() && !is_page()) {
		$content .= '<br>[wzslider lightbox="true"]<br>[fu-upload-form title="Envie sua foto desta receita"]
[input type="file" name="photo" id="ug_photo" description="Envie foto apenas de sua autoria.<br>Tamanho m&aacute;ximo do arquivo: 150KB.<br>Envie e aguarde a pagina recarregar."]
[input type="submit" value="Enviar"] [/fu-upload-form]';
	}
	return $content;
}
add_filter('the_content', 'add_post_content');

http://ww.wp.xz.cn/extend/plugins/frontend-uploader/