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.… or…

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?