Multiple tracking codes are useful or segmenting your tracking data into different projects, allowing you to have separate dashboards for different sections of your site or web app. Simply include the project tokens for different projects on each page. You can either track all events, pageviews and people on all the sites, or selectively track different activity on the different sites.

We at GoSquared use this functionality ourselves to understand how our entire platform is performing as a whole as well as segmenting areas (such as this documentation area) to see how specific areas are performing over time.