I tried to just test a script from amazon for their affiliate program

i just implemented it at the basic HTML editor on homepage for a short test. put this in between a div where i want to load this lil window.

<script charset="utf-8" type="text/javascript">

amzn_assoc_ad_type = "responsive_search_widget";

amzn_assoc_tracking_id = "widgetsamazon-20";

amzn_assoc_link_id = "5H3NR6KLIMLLKOOL";

amzn_assoc_marketplace = "amazon";

amzn_assoc_region = "US";

amzn_assoc_placement = "";

amzn_assoc_search_type = "search_widget";

amzn_assoc_width = "auto";

amzn_assoc_height = "auto";

amzn_assoc_default_search_category = "";

amzn_assoc_default_search_key = "";

amzn_assoc_theme = "light";

amzn_assoc_bg_color = "FFFFFF";

</script>

<script src="//z-na.amazon-adsystem.com/widgets/q?ServiceVersion=20070822&Operation=GetScript&amp;ID=OneJS&amp;WS=1&amp;MarketPlace=US"></script>

it works well,

but my question ist how do i have to do it correctly. Because every time i safe the website again if i change anything on it, it doubles the search widget on the website. why does this happen ? 

cheers joe