I just read the question asking if Pokemon: GO! counts as active for the sake of hatching eggs when the screen is locked; the result was that it does not.
So what about if it is split screen? I'd like to do a bit of running (couch->5k style) and was planning to use the app "Run. Zombies!" to do it but it would be great to hatch eggs at the same time.
Edit: Turns out split screen is awkward to enable on my phone, so for the purpose of the question, assume I'm not using any specific method of split-screen or any specific phone. If you know it works for one method/phone, let me know! If you know it doesn't work for another method/phone... let me know that too! :)