Google Analytics
タグアシスタント

複数タグは
Universal Analytics
analytics.js

https://developers.google.com/analytics/devguides/collection/analyticsjs/advanced#multipletrackers

ga('create', 'UA-XXXX-Y', 'auto');
ga('create', 'UA-12345-6', 'auto', {'name': 'newTracker'});  // New tracker.

ga('send', 'pageview');
ga('newTracker.send', 'pageview'); // Send page view for new tracker.