I realize this is quite an old question, but since external monitors on displayports/HDMI don't play nice with Linux I might as well try to help anyone Googling this in the future.
I use arch myself, but since you use xrandr (randr) to set up your monitors I suppose the same instructions should work.
There is very good documentation on the arch forum on using xrandr and multihead (for several monitors).
If you get an image on both external monitors than what you need to do is to use relative positioning with the keywords
You can also use absolute positioning with the keyword
--pos when you know the resolution of your screens and want to have them at weird locations relative to each other.
To make any changes to settings in xrandr permanent you probably need to add these to a configuration file, which depends on your system. I do not know Fedora, so I am not much help here. But I am sure there are plenty of people who do.
If you use gnome there is however an easier solution. Use the screen widget in your tools menu and set the monitors to multiple screens. You can then push the "rearrange screens" button and drag them relative to each other.
I have a different issue when using my HP monitors from laptop bay displayports. I know many HP monitor users share this. Therefore, I add my solution here.
Problem: It will not recognize the external monitor because the resolution of the screens read in lacks the supported resolution by the screen. As a result, the monitor stays asleep/goes to sleep. And it does not help to add the resolution using xrandr.
Solution (work-around): In this case, the only way of getting the computer to enable the screen with the correct resolution is to boot up the computer before connecting it to the laptop bay, but do not log in yet. Connect the computer to the screen through the bay before logging in. At that time the computer recognizes the correct resolutions and all screens will work also after logging in.
It is virtually impossible to fix after logging in with my laptop bay. Disconnecting from the bay and reconnecting does nothing. The monitor just stays asleep.
I hope this helps someone using HP monitors on Linux and a displayport/HDMI through a laptop bay.