How to get 2 android apps working simultaneously?
That's a really good question! Thank you for asking it though.
On Android Programming, There is something we call, Activities LifeCycle
Imagine, when you pressed the home Button, The current Activity is going to onPause() method which it stops the Activity and it's not longer active because this is the Android Activity's lifecycle.
So, for better underestanding, The developer or those Application's programmers have to use something like Services which it can perform long-running operations in the background and does not provide a user interface.
And after that, you should be able to use those features together.