How to fix automatic redirects?

Those aren’t really redirects, the “Hash” part of a URL (the # and anything after that) are purely client side and will not trigger another request to your server.

The reason for it is AddThis. Here’s an explanation as to why they are doing that:
What is AddThis Click Tracking?

You can disable it by adding an option to the addthis config:

<script type="text/javascript"> 
var addthis_config = {
    data_track_clickback: false 
} 
</script>

Where and how to insert this depends on how AddThis is embedded in your site.