[Pro Sites] Pro Sites Update Database Error

After updating Pro Sites to Version 3.6.0, I noticed the following in our server error logs. Please advise what kind of issues this may cause and how to address. Thank you!

[16-Jan-2019 00:04:16 UTC] WordPress database error Multiple primary key defined for query ALTER TABLE wp_pro_sites ADD PRIMARY KEY  ('blog_ID') made by require(
'wp-blog-header.php'), require_once('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), include_once('/plugins/pro-sites/pro-sites.ph
p'), ProSites->__construct, ProSites->install, dbDelta