Google Tag Manager Patch - Only output tag once. https://wordpress.org/plugins/google-tag-manager/

google-tag-manager.patch

Index: trunk/google-tag-manager.php
===================================================================
--- trunk/google-tag-manager.php	(revision 1182053)
+++ trunk/google-tag-manager.php	(working copy)
@@ -11,6 +11,8 @@
 
 class google_tag_manager {
 
+	public static $output_once = false;
+
 	public static function go() {
 		add_filter( 'admin_init', array( __CLASS__, 'register_fields' ) );
 		add_action( 'wp_footer', array( __CLASS__, 'print_tag' ) );
@@ -28,7 +30,7 @@
 		<?php
 	}
 	public static function print_tag() {
-		if( ! $id = get_option( 'google_tag_manager_id', '' ) ) return;
+		if( self::$output_once || ! $id = get_option( 'google_tag_manager_id', '' ) ) return;
 		?>
 <!-- Google Tag Manager -->
 <noscript><iframe src="//www.googletagmanager.com/ns.html?id=<?php echo $id; ?>"
@@ -40,6 +42,7 @@
 })(window,document,'script','dataLayer','<?php echo $id; ?>');</script>
 <!-- End Google Tag Manager -->
 		<?php
+		self::$output_once = true;
 	}
 }