Clicking on a title within All Subscriptions gives you the option to clone subscriptions from another title into a new title.
Clicking "Clone Subscribers From" (3) will open up a modal.
You can search for other titles, and clone all of the subscribers from that title into this new title!
If they're already on this list, they won't get doubled up.
*Cloning Subscriptions currently only work for products which can be subscribed to, we are working on a solution for one-shots and non-subscribable products as well.