If you'd like to add multiple buttons to the same page, you will need to assign a custom id to each additional button element that you add and then include that id at the end of the URL in the script tag.
Example of Code Snippet for Additional Button
Replace the "teachworks-booking-button" ID with a different ID and then include it at the end of the URL in the script:
<div id="teachworks-booking-button-extra"></div><script>document.write('<script type="text/javascript" src="https://teachworksdemo.teachworks.com/booking_button.js?token=dtsksnjfXLwhOyLf33l4RA&custom_id=teachworks-booking-button-extra"><\/script>');</script>NOTE: In the example above, the custom id is "teachworks-booking-button-extra", but you can set this to anything that makes sense to you.