loadingMixpanelTwice.js

/* After Loading the Snippet */

/* You can namespace each instance of the Mixpanel JavaScript Library */

/* First Instance */
mixpanel.init("Token1", {}, 'developmentProject');

/* Second Instance */
mixpanel.init("Token2", {}, 'productionProject');

/* Now you can send data to either using the namespace and they'll go to separate projects */
mixpanel.developmentProject.track('Event');
mixpanel.productionProject.track('Event');