Having two Whatsapp, Facebook messenger accounts (and many more apps) is now easy with Dual Messenger. This allows us to use two different accounts in one chatting app. Samsung has given this as a default feature in the latest Oreo firmware. Not all apps are supported by Dual Messenger. Please check the compatible apps in the Dual Messenger settings itself.
Steps to install Dual Messenger in Galaxy phones and in other Samsung phones as well running Oreo. Check it out by performing the following steps.
1. Go to Settings and select 'Advanced features'
2. Tap on the 'Dual Messenger'
3. The next screen shows the available apps that can be installed again to use with a second account. The apps that includes Whatsapp, Facebook, Facebook messenger, Telegram, etc. Follow the on-screen instructions and you are done.