Yes! With the free account, you can have up to 5 stores added to the same Printify account. If you're a Premium plan subscriber, you can add up to 10 stores to the same account.
The stores can be based on the same or another sales channel. For example, you can add a Shopify and a WooCommerce store, or 2 Shopify stores.
How can I add another store that is based on the same sales channel?
Make sure you are logged out of your sales channel account (e.g. Shopify).
Proceed to integrate the additional store from the Printify side (click Manage My Stores → Add new store) and follow the integration steps.