Double featured image on home page

When I installed 1.4 the plugin I got an error message.

“Warning: Cannot modify header information – headers already sent by (output started at /home4/njnnet5/public_html/njn/wp-admin/includes/template.php:1698) in /home4/njnnet5/public_html/njn/wp-content/plugins/jetpack/class.jetpack.php on line 3902
Warning: Cannot modify header information – headers already sent by (output started at /home4/njnnet5/public_html/njn/wp-admin/includes/template.php:1698) in /home4/njnnet5/public_html/njn/wp-includes/pluggable.php on line 896″

I fixed that error.

Now I have double featured images on the home page

https://njnnetwork.com

I found this thread on the same problem https://www.ads-software.com/support/topic/trouble-with-featured-image-for-posts-on-mobile

Could you try the following:
1.Go to this page: https://helpmeviz.com/wp-admin/options.php
2.Look for this option: wp_mobile_featured_images 3.Make sure it is set to 0 4.Save your changes

The solution does not work for me since I don’t have the string “wp_mobile_featured-images” in /wp-admin/options.php.

The string does not appear anywhere under my root directory/

Is the string located some where else? Or is there another solution?

Thanks. SP

https://www.ads-software.com/plugins/jetpack-mobile-theme-featured-images/