The Facebook app only supports one registered account at a time – but what if you need one for work and one for your private life? Normally, you would need to log out and log back in each time you need another account. However, your OnePlus device offers a much better solution.
The main reason why you can only sign up for one active Facebook account per session is probably due to a security and privacy concern. You do not want to risk running a handful of accounts in the same active session as they can be easily accessed at the same time.
To start running two separate Facebook accounts on your OnePlus phone, go to your system settings and go to the Utilities section. Find the "Parallel apps" section and go to these settings to see more details about the feature.
Displays a list of currently installed apps supported by the feature. These will most likely be filled with social media apps. Find the "Facebook" option and set the switch to "On" to create a "parallel" version of the app. This means that the main Facebook app is cloned to create a separate instance of it, giving you essentially two different apps. Cool!
On the way to your app drawer, you should notice two versions of the Facebook app below this point. The new "Parallel" version is marked in the lower right with the orange icon for parallel apps. Open the new version of the app and sign in with a different account so you can use two Facebook accounts at the same time.
If you ever wanted to remove the parallel version of the Facebook app, return to the page "Parallel apps" back and turn off the switch. You will receive a message informing you that all data will be deleted if you deactivate the parallel version of the Facebook app. Confirm your selection by clicking the "OK" button. It will be removed from your system immediately.