It's fine. As long as it's not causing any problems, it's absolutely fine. ATi's been doing that for quite a while (since early 2000s).
It usually happens with old video cards of "ATi" era, it shows two devices because they have two RAMDACs, and thus essentially two video cards. %)
Nothing to worry about for the device...don't try to disable it if it's not causing any problems....
The only thing you should worry about is for your drivers to be up-to-date, really. %)