Hi there, @MEWW . Thanks for taking the time to reach out to the Shopify Community Forums to look for some information around your Instagram question! My name is Imogen. It’s good to meet you!
At this time, you can only have one Instagram Account linked to a Shopify Store. This means that you won’t be able to have a second Instagram account linked to the store that links to this second collection.
Is this a particular reason why you’re looking to achieve this functionality? Are the products between these two collections dramatically different from one another to a degree that customers would get confused to see them paired together on one Instagram page?