We're back with one of those Android tricks you love so much, in this case a trick for Android Nougat users that will allow us to duplicate WhatsApp in Android Nougat's multi-window mode.
Well, besides allowing us to duplicate WhatsApp in Android Nougat's multi-window mode , this will also allow us to duplicate almost any application that accepts this new multi-window or split-screen mode by default in Android 7.0 and later.
To duplicate WhatsApp in Android Nougat's multi-window mode, allowing you to chat with two contacts from your WhatsApp address book simultaneously without constantly switching between chats, you simply need to download and install a completely free application available directly from the official Android app store, the Play Store or Google Play.
The application that responds to the descriptive name of Parallel Windows for Nougat, as its name indicates, is only compatible with versions of Android 7.0 onwards. Right at the end of the post I leave you a direct link for you to download and install it directly from the Google Play Store
But what does this app really do?

Parallel Windows for Nougat will take Android multitasking to another level through this multi-window or split-screen feature, which is already enabled by default in Android versions 7.0 and later. It offers the possibility of having two instances of the same application running simultaneously , just as we can duplicate WhatsApp in this multi-window with a simple gesture. We will be able to do this with any application that allows the use of this split-screen or new Android Nougat multi-window feature.
Simply by installing Parallel Windows for Android Nougat, running it for the first time, and granting the necessary permissions—including screen overlay permissions and access to your Android's accessibility settings—the application will display its settings interface. From here, you can configure the tile or action area that will launch the hidden sidebar. This hidden sidebar, in addition to being able to duplicate any application that supports Android Nougat's multi-window feature , also offers other interesting options such as adding an application box as a sidebar, or a sidebar that displays recently used applications.

In short, even though it's still an Alpha version and I haven't been able to get this dual-screen mirroring working with apps like Telegram, it has worked quite well for me with apps like Google Chrome, WhatsApp, and generally with apps that support Android Nougat's multi-window mode.
I invite and recommend that you take a look at the embedded video I've left at the beginning of this post. In it, besides showing you the correct way to duplicate WhatsApp in Android Nougat's multi-window mode , I also try it with other applications like Telegram (without success), the Google Chrome browser (successfully, but after several attempts), and Samsung's native web browser, which, as with Telegram, I couldn't use to duplicate the app and have two instances of it in Android Nougat's multi-window mode.

Hopefully, the app developers will soon release a new version via update that fixes all these minor bugs and errors. These kinds of apps, while promising great success, can actually become incredibly useful in our daily Android use.