How handle pages with "read more" text query strings?

[DougHartline]

My site has hundreds of keyword content landing pages that contain one or two sections of "read more" text that work by calling the page and changing a ChangeReadMore variable. This causes the page to currently get indexed 5 times (see examples below plus two more with anchor tag set to #sectionReadMore2

This causes Google to include the first version of the page which is the canonical version and exclude the other 4 versions of the page.  Google search console says my site has 4.93K valid pages and 13.8K excluded pages.

My questions are:

1. Does having a lot of excluded pages which are all copies of included pages hurt my domain authority or otherwise hurt my SEO efforts?

2. Should I add a rel="nofollow" attribute to the read more link? If I do this will Google reduce the number of excluded pages?

3. Should I instead add logic so the canonical tag displays the exact URL each time the page re-displays in another readmore mode? I assume this would increase my "included pages" and decrease the number of "excluded pages".  Would this somehow help my SEO efforts?

EXAMPLE LINKS

https://www.tpxonline.com/Marketplace/Used-AB-Dick-Presses-For-Sale.asp

https://www.tpxonline.com/Marketplace/Used-AB-Dick-Presses-For-Sale.asp?ChangeReadMore=More#sectionReadMore1

https://www.tpxonline.com/Marketplace/Used-AB-Dick-Presses-For-Sale.asp?ChangeReadMore=Less#sectionReadMore1