When adding Google Analytics in DTM, consider the following:
1. What is 'tracker variable name' when page code is present?
2. Why is upgrade from GA suite to Universal GA suite affecting DTM implementation?
DTM now supports Universal Analytics in a native integration. More information available here: https://marketing.adobe.com/resources/help/en_US/dtm/google_universal_analytics.html
3. Why is GA e-commerce tracking not working/what are best practices for e-commerce tracking?
Best practice is to enable support for Google Universal Analytics Premium features. There is a check box for premium Google Universal Analytics features in the tool (General group). This option enables the max dimensions and metrics increase from 20 to 200.
4. Why is the Google Analytics beacon firing twice?
The beacon can fire twice if the tool is installed and it is called in a rule. If you have recently moved to using the installed Google Analytics tool, check the rules and custom code sections for GA code. If the code is present in multiple places, it causes two beacons to fire.