Add functionality to add multiple trackers

It would be nice if you could make it possible to add multiple trackers in this plugin, without the need of using the custom tracker code option.

I have an aggregate + site specific account for each of my sites.

Here is the google documentation
https://developers.google.com/analytics/devguides/collection/analyticsjs/advanced#multipletrackers

Let me know if you can use any help

https://ww.wp.xz.cn/plugins/nk-google-analytics/