Weird issue with appending our website address to the end of our urls

We are having a strange issue with our website address being appended to the end of our urls. Examples.
www.bordnerinstall.com/www.bordnerins… or
www.bordnerinstall.com/roofing/www.bo…

We have found thousands of visitors exiting the site because they’ve encountered the 404 error page due to the incorrect urls.

Any idea how this is happening?

I have temporarily removed all our iis url rewrite ruiles (except the 2 you helped setup for www canonization and removing /index from every page.) Is it possible one of these rules is causing this?