XF 1.4 Duplicate post - ad_message_below

Hey Everybody,

I am using Google Adsense and have noticed that messages posted in my forums are being duplicated when they have adsense code attached to them. Here is my code:

<xen:if is="!{xen:helper ismemberof, $visitor, 5, 6, 7}">
<xen:if is="{$post.position} % {$xenOptions.messagesPerPage} == 5 AND !{$message.conversation_id}">
<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
(adsbygoogle = window.adsbygoogle || []).push({});

So I only show ads on the every 5 messages, I noticed that in 2 separate posts, the message that was supposed to have this code attached has been duplicated. Does anyone know what this may be or have experienced this? Thanks!
What I'd like to try is only apply the ad code if the post has existed for a minute to see if it's a weird timing issue, does anyone know how I can check how long a post has lived?
I believe I may have fixed this by adding a " AND !{$post.canEdit}" to the check, this should prevent the ad from showing up if the user can edit the post (within the edit time limit)