Duplicate Meta description on shared node across multiple subdomains
I haven't used that module (looks cool!), but it does depend on metatag, which is probably what's providing the title &amp; description fields. The metatag module saves its configuration in a database table metatag_config, which is probably shared across all of your subdomains.

It looks like you can have tokens in your config, so for example, we use [node:title] [site:name] for our page title config. And if you wanted an unique title for each subdomain, you could just specify a separate site name for each one.

We use subdomains (www, m, staging, dev, etc) and we're fine to share the node's title &amp; description across all of them. The thing we do want unique is the canonical meta tag, so if a search engine comes across duplicated content on a subdomain, it won't take anything away from the original. So we'll specify the full domain in the canonical url like this:

https://www.example.com/[current-page:url:path]