Starlink does not do load balancing or switching, instead both terminals will be active utilizing time division duplexing.

3rd party edge routers can be used to support load balancing. If using this type of set up, you can bypass the Starlink routers, and connect both dishes to the 3rd party router. If load balancing is supported, then the router will automatically switch its connection to the dish provided the best level of service in the moment.