How to replace with old GA script?

Hi, first of all thank you for this nice plugin.

I’m facing a problem and that is , i’ve already have had google analytics script in the footer of my site.
now i don’t know whether i should remove it after activating your plugin or not!?

i mean, i added my GA id to the plugin and it added a script in the footer, but there was my old script too.
after that i removed my old script but the realtime users got half (dropped from 1400 to 600) and when i took back my old script, it raised high again.

now my question is how should i replace your plugin with my old footer script?
for your information, i use wp rocket for caching.

The page I need help with: [log in to see the link]