David Garcia

According to WordPress documentation, by default, clicking the .more-link anchor opens the web document and scrolls the page to section of the document containing the named anchor (#more-XXX). This section is where writers choose to place the  tag within a post type. With this plugin we can prevent this scroll down.
Visit the <a href="http://www.seocom.es/" rel="nofollow ugc">Seocom website</a> for more information.

Prevent Read More Scroll

Prevents the page scroll that occurs when clicking in the read more links.

termel

Simply prevent duplicate submissions by blocking the submit button while submitting

Gravity Forms Prevent Duplicates

Does the job

Simply prevent duplicate submissions by blocking the submit button while submitting

Prevent Read More Scroll vs Gravity Forms Prevent Duplicates