java - press home key button and reinitialize the application

My application activity is facing a scenario when user press Home button on android phone.

I have used OnPause() method . this i called when user press Home key. and Normal cicumstances when user launch the app again, it calls the onResume() method of the activity.

But sometimes, when user re-launch the application, it opens the Launcher Activity(instead of calling the current activity.)

So I am confused. in my phone it always calls the current activity. But sometime on another phone, i see that it calls the launcher activity and application starts again.

How to solve this issue? Am i doing something wrong?