Split test pop up - OR - How to specify one of the active pop over creatives via a Javascript call/v

Hey guys, love the Pop Up plugin!

I would like to split test several simultaneous pop overs - how can I do that?
I tried to leave multiple ones active, and what happens is only the first pop up shows every time on every page load.

Alternatively - is there a way to call specifically one of the active pop ups via a Javascript variable or call in the webpage itself?

Thanks!