Identity leak – network subdomain site includes links/query results from another

I’ve got the plugin running on a network site altc-alt.ac.uk and successfully created another network on the site with the domain oer15.oerconf.org. Recently I created another network oer16.oerconf.org, which also seems to work ok.

I’ve however noticed when logged in to oer15.oerconf.org that some of the queries return results for oer16.oerconf.org, for example, the log out links are https://oer16.oerconf.org/wp-login.php?action=logout…

Is this related to how the server is configured rather than how the plugin works? I noticed server config is mentioned on the github page

https://wordpress.org/plugins/wp-multi-network/