Should I create a new on-page tag for an existing UA tracking or use the existing?

Question

I have used the Google Universal Analytics for many years and will now use Google Analytics 4 instead. So in Google analytics Admin I created a new "on-page tag" and placed it in my site together with the old UA tracking code. But should I have removed the old UA tracking code before or should I keep both the old one and the new one there?

Also, should I have used the existing "on-page tag" instead of add the new one, the only difference between them is the ID. The existing on-page tag has the same ID as the old UA code, but the new on-page tag has a new ID.

Answer 1

The id is different for GA4, so you did right making a new one.

Whether to keep both or not is completely up to you. The general suggestion is to keep both and use UA until GA4 gets over a year of data for you to be able to conduct year over year comparisons.