My assumption is that you're working with an Eyefinity 4x1 span.
My assumption why you have 4 cloned screens in P3D is that you've not set within P3D the actual spanned resolution and it's cloning a single screen resolution to all the screens. This is typically what Eyefinity does if you have an Eyefinity span but the game has a single display resolution set in it. Set it to the proper Eyefinity 4x1 resolution within P3D and that should take care of the cloning issue.
How many of the displays in the Eyefinity span are projectors? I should be able to walk you through it a bit more once I know more about your setup. We'll get it figured out. No worries.