Two apps that share screen space can be implemented in Android 6.1. Some developers found the features to run two apps at the same time on the screen in Android 6.0 when the version of Android was in the development stage. Function was however never with the final version of the operating system and many have wondered where it went.
According to a new android 6.1 rumor, it seems that the android split screen function needed a little more time to develop and that function will be included in Android 6.1, which according to the source will be released in June.
The late date makes us, however, to guess that it basically only Nexus devices will have time to get the update before it is time to start to look towards Android 7, which should be released sometime next fall.
Whether the feature will only show up on tablets, or if there is no delimiter in the resolution, size, or performance of the devices remains to be seen.
Worth mentioning is that some models of Samsung phones (mostly Note series) and tablets have had features to run two apps on screen for a few years now.