How to make a dual-monitor setup?

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If you have a video card that support two monitors just plugin it to Fedora and it will extend your display not mirror it unless you choose to. To check go to control panel ->screen and doble click on the first one and see the propierties to change primary and secondary and other features. Since you have Radeon card not sure if will be a different way.

You can always booth with Live Media and test.